cast to void *' from smaller integer type 'int

What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Get the address of a callback function to call dynamically in C++, error: call of overloaded function ambiguous, error: cast from to unsigned int loses precision [-fpermissive]. SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); Put your define inside a bracket: #define M_TABLE_SIZE (64*1024) Now, you can do: static const void* M_OFFSET = (void*) M_TABLE_SIZE; without a problem. @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. you can pass the int value as void pointer like (void *)&n where n is integer, and in the function accept void pointer as parameter like void foo (void *n); and finally inside the function convert void pointer to int like, int num = * (int *)n;. C++ how to get the address stored in a void pointer? Why is this sentence from The Great Gatsby grammatical? Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Once you manage to make this cast, then what?! This page was last modified on 12 February 2023, at 18:25. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. What is the purpose of this D-shaped ring at the base of the tongue on my hiking boots? But this code pass the normal variable .. Thanks for contributing an answer to Stack Overflow! - the incident has nothing to do with me; can I use this this way? ../lib/odp-util.c:5489:33: note: expanded from macro 'SCAN_PUT_ATTR' The problem is not with casting, but with the target type loosing half of the pointer. rev2023.3.3.43278. The following behavior-changing defect reports were applied retroactively to previously published C++ standards. I have the following function and when I compile it under VS.NET 2005, the following compile warnings show up: Warning1warning C4311: 'type cast' : pointer truncation from 'void *' to 'long'c:\temp\testone\lib\utils.c56Warning2warning C4312: 'type cast' : conversion from 'unsigned long' to 'void *' of greater sizec:\temp\testone\lib\utils.c56, Code Snippet If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. The main point is: a pointer has a platform dependent size. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @Dinesh: could you please 1) show us those. (int) pthread_self() 64int48intuintptr_t (unsigned int) SCAN_PUT_ATTR(key, ATTR, skey, FUNC); The correct answer is, if one does not mind losing data precision. what happens when we typecast normal variable to void* or any pointer variable? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Thanks. Using Kolmogorov complexity to measure difficulty of problems? How to use Slater Type Orbitals as a basis functions in matrix method correctly? Disconnect between goals and daily tasksIs it me, or the industry? Thanks for contributing an answer to Stack Overflow! What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. I recall there was a TreeNode(int) early on prior to 1.0 release I can't remember why I removed it, if I should felt it was easy enough to cast to (void*) or if it was because it created type inference conflict at the call site. you can just change architecture to support 32 bit compilation by all below in in Build Settings. Can I tell police to wait and call a lawyer when served with a search warrant? You are correct, but cocos actually only uses that address as a unique id. Floating-point conversions And, most of these will not even work on gcc4. So the compiler is very picky here and the correct solution to make the code compile again and still let it show the exact same behavior like in Xcode 5.0 is to first cast to an integer type with a size that matches the one of a pointer and to then do a second cast to the int that we actually want: I am using size_t here, because it is always having the same size as a pointer, no matter the platform. The dynamic_cast<>operator provides a way to check the actual type of a pointer to a polymorphic class. From the question I presume the OP does. A cast specifies a conversion from one type to another. Thanks for pointing that out. And in this context, it is very very very common to see programmers lazily type cast the. If you cast an int pointer int, you might get back a different integer. Connect and share knowledge within a single location that is structured and easy to search. If that happens soon after the call to pthread_create() then you have a race condition, because there's a chance that the thread will attempt to read x's value after it's life has ended, which invokes undefined behavior. Find centralized, trusted content and collaborate around the technologies you use most. (void *)i Error: cast to 'void *' from smaller integer type 'int'. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? This will get you a pointer from a 32 bit offset: A function pointer is incompatible to void* (and any other non function pointer). But I don't want to edit code in "EAGLView.mm" because it's a "library file". This is memory reinterpretation - a completely unacceptable way to do what the OP is trying to do. Pd = Pa; Similarly, Pc may be type cast to type int and assigned the value Pa. 1. should we also have a diagnostic for the (presumed) user error? use $(ARCHS_STANDARD_32_BIT) at Architecture instead of $(ARCHS_STANDARD). returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); What is the purpose of non-series Shimano components? The int data type is the primary integer data type in SQL Server. To learn more, see our tips on writing great answers. How to tell which packages are held back due to phased updates, Identify those arcade games from a 1983 Brazilian music video. You think by casting it here that you are avoiding the problem! So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. Just edited. If you are planning to use pthreads and you are planning to pass the pass function to pthread_create, you have to malloc/free the arguments you are planning to use (even if the threaded function just need a single int). Mutually exclusive execution using std::atomic? Replacing broken pins/legs on a DIP IC package, AC Op-amp integrator with DC Gain Control in LTspice. Typically, long or unsigned long is . Basically its a better version of (void *)i. The pointer doesn't actually point to anything, but it's the result of an earlier cast from an integer to a pointer (e.g. As Ferruccio said, int must be replaced with intptr_t to make the program meaningful. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? Find centralized, trusted content and collaborate around the technologies you use most. That could create all kinds of trouble. But I'm nitpicking .. The value of float variable is= 37.75. SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); The compiler issues the "cast from integer to pointer of different size" warning whenever the value of an integer is converted to a pointer, especially when the memory allocated to a pointer is smaller than the memory allocated to an integer data type. While working with Threads in C, I'm facing the warning, "warning: cast to pointer from integer of different size". What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Why is this sentence from The Great Gatsby grammatical? I don't see how anything bad can happen . Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? It generally takes place when in an expression more than one data type is present. On most platforms pointers and longs are the same size, but ints and pointers often are not the same size on 64bit platforms. The nature of simulating nature: A Q&A with IBM Quantum researcher Dr. Jamie We've added a "Necessary cookies only" option to the cookie consent popup. SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); reinterpret_cast is a type of casting operator used in C++. If the value is ever used as pointer again that will prove to be an extremely bad idea. that any valid pointer to void can be converted to this type, then To access the object value, use the * dereference operator: int * p; assert (p == null ); p = new int (5); assert (p != null ); assert (*p == 5); (*p)++; assert (*p == 6); If a pointer contains a null value, it is not pointing to a valid object. cast operators [edit] When an expression is used in the context where a value of a different type is expected, conversionmay occur: intn =1L;// expression 1L has type long, int is expectedn =2.1;// expression 2.1 has type double, int is expectedchar*p =malloc(10);// expression malloc(10) has type void*, char* is expected A sane compiler may throw a warning on lines like this but by no way it should throw an error, because this code is NOT wrong, it is just potentially error-prone, but can be perfectly valid. Remarks. 471,961 Members | 900 Online. Thanks for contributing an answer to Stack Overflow! ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] equal to the original pointer: First you are using a define, which is not a variable. How do I set, clear, and toggle a single bit? From that point on, you are dealing with 32 bits. privacy statement. Yesterday, I updated Xcode to the newest version (5.1 (5B130a)) to compatible with iOS 7.1. Does Counterspell prevent from any further spells being cast on a given turn? Does a summoned creature play immediately after being summoned by a ready action? If you write ((char*)ptr + 1), it will advance the pointer 1 byte, because a "char" is 1 byte. C/C++ , Cerror: cast to 'void *' from smaller integer type 'int'. ERROR: incompatible integer to pointer conversion assigning to 'string' (aka 'char *') from 'int', error: cast to 'string' (aka 'char *') from smaller integer type 'int' [-Werror,-Wint-to-pointer-cast], error: incompatible integer to pointer conversion assigning to 'string' (aka 'char *') from 'int' C, warning: initialization of 'unsigned char' from 'uint8_t *' {aka 'unsigned char *'} makes integer from pointer without a cast [-Wint-conversion], Minimising the environmental effects of my dyson brain. Why does setupterm terminate the program? When is casting void pointer needed in C? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. You cannot just cast the 32-bit variable to a pointer, because that pointer on a 64-bit machine is twice as long. Is it possible to create a concave light? Linear regulator thermal information missing in datasheet. In my case, I was using a 32-bit value that needed to be passed to an OpenGL function as a void * representing an offset into a buffer. I need to cast the int from the first function so that I can use it as an argument for the second function. Why does Mister Mxyzptlk need to have a weakness in the comics? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. How Intuit democratizes AI development across teams through reusability. However the actual code in question contains an explicit c-style cast to int. XCode 5.1 is change all architecture to 64 bit. Even if you are compiling your program for a 32-bit computer, you should fix your code to remove these warnings, to ensure your code is easily portable to 64-bit. This forum has migrated to Microsoft Q&A. static_cast on the other hand should deny your stripping away the const qualifier. If you convert (void*) to (long) no precision is lost, then by assigning the (long) to an (int), it properly truncates the number to fit. Replacing broken pins/legs on a DIP IC package, How to handle a hobby that makes income in US. Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. x is a local variable and its lifetime ends as soon as control leaves the scope it was defined in. The problem was there before, you just are being notified of it. Since gcc compiles that you are performing arithmetic between void* and an int (1024). Taking the above declarations of A, D, ch of the . So you could do this: Note: As sbi points out this would require a change on the OP call to create the thread. B language was designed to develop . If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . The most general answer is - in no way. void* -> integer -> void* rather than integer -> void* -> integer. For the remaining integral types, the result is the value of the enum if it can be represented by the target type and unspecified otherwise. The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. You may declare a const int variable and cast its reference to the void*. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. C99 defines the types "intptr_t" and "uintptr_t" which do . ^~~~~~~~~~~~~~~~~~~ Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? If the object expression refers or points to is actually a base class subobject of an object of type D, the result refers to the enclosing object of type D. Otherwise, the behavior is undefined: When the target type is bool (possibly cv-qualified), the result is false if the original value is zero and true for all other values. Yeah, the tutorial is doing it wrong. It is easier to understand and write than any other assembly language. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. If this is the data to a thread procedure, then you quite commonly want to pass by value. Passing arguments to pthread_create - invalid conversion from void(*)() to void(*)(void*). Thus as a result it may be less error prone to generate a pointer dynamcially and use that. Returns a value of type new-type. Casting arguments inside the function is a lot safer. Is pthread_join a must when using pthread in linux? long guarantees a pointer size on Linux on any machine. I have looked around and can't seem to find any information on how to do this. Noncompliant Code Example (memset())For historical reasons, certain C Standard functions accept an argument of type int and convert it to either unsigned char or plain char. The OP wanted to convert a pointer value to a int value, instead, most the answers, one way or the other, tried to wrongly convert the content of arg points to to a int value. Bulk update symbol size units from mm to map units in rule-based symbology. Getting Command /bin/sh failed with exit code 65 Error with Xcode 5.1 . byte -> short -> char -> int -> long -> float -> double. If you call your thread creation function like this, then the void* arriving inside of myFcn has the value of the int you put into it. The preprocessor will replace your code by this: This is unlikely what you are trying to do. Before I update Xcode, my project still can build and run normally with all devices. In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. Not the answer you're looking for? I think the solution 3> should be the correct one. how to cascade 2d int array to 2d void pointer array? My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. Cast characters to unsigned char before converting to larger integer sizes Created by Robert Seacord, last modified by Jill Britton on Oct 03, 2022 Signed character data must be converted to unsigned char before being assigned or converted to a larger signed type. There's no proper way to cast this to int in general case. Click to see the query in the CodeQL repository. 7.1 New Cast Operations The C++ standard defines new cast operations that provide finer control than previous cast operations. And in the function you get the value of the pointer by using the dereference operator *: Please read why glib provide macros for this kind of conversions, there's no need to repeat the text here. @jackdoe: It's a waste of human life to write code that "you may need in the future". error: cast from pointer to smaller type 'unsigned int' loses information. If the original pointer value represents an address of a byte in memory that does not satisfy the alignment requirement of the target type, then the resulting pointer value is unspecified. Hence there is no loss in data. But, sure, in that specific case you can pass a local variable address, type casting integer to void* [duplicate]. p-util.c.obj "-c" ../lib/odp-util.c All float types are to be converted to double. The subreddit for the C programming language, Press J to jump to the feed. If the original type is a void *, converting to an int may lose date on platforms where sizeof(void *) != sizeof(int) (which is true of LP64 programming model). The nature of simulating nature: A Q&A with IBM Quantum researcher Dr. Jamie We've added a "Necessary cookies only" option to the cookie consent popup. A cast is a way of explicitly informing the compiler that you intend to make the conversion and that you are aware that data loss might occur, or the cast may fail at run time. Making statements based on opinion; back them up with references or personal experience. How to get the error message from the error code returned by GetLastError()? ^~~~~~~~~~~~~~~~~~~~~ Don't pass your int as a void*, pass a int* to your int, so you can cast the void* to an int* and copy the dereferenced pointer to your int. By clicking Sign up for GitHub, you agree to our terms of service and 1. A missing cast in the new fast > enumeration code. Based on the design of this function, which modification is right. Keep in mind that thrArg should exist till the myFcn() uses it. Well occasionally send you account related emails. "-I.." "-Iinclude\openflow" "-I..\include\openflow" "-Iinclude\openvswitch" "-I..\include\openvsw then converted back to pointer to void, and the result will compare The result is the same as implicit conversion from the enum's underlying type to the destination type. . Making statements based on opinion; back them up with references or personal experience. Find centralized, trusted content and collaborate around the technologies you use most. I am an entry level C programmer. If the value in a pointer is cast to a different type and it does not have the correct alignment for the new type, the behavior is undefined. Evaluate integer expressions in a larger size before comparing or assigning to that size.Note that (time_+t)-1 also complies with INT31-C-EX3. Offline ImPer Westermark over 11 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. Not the answer you're looking for? How do I check if a string represents a number (float or int)? There are ways to prevent this: pass a dynamic allocated argument if your not the passing thread is not static or if your argument is a local variable, otherwise there is no issue. Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. Use returnPtr[j] = (void *) ((long)ptr + i); ). What does casting to void* does when passing arguments to variadic functions? What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? @Shahbaz you could but I will not suggest to a C newbie to use globals. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. SQL Server does not automatically promote . The best way is, if one can, do not do such casting, instead, if the same memory address has to be shared for pointer and int (e.g. Please note that the error I am receiving is "cast to smaller integer type 'int' from 'string' (aka 'char *')" referencing line of code: while (isalpha(residents[i].name) == 0). rev2023.3.3.43278. Find centralized, trusted content and collaborate around the technologies you use most. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. @DavidHeffernan I rephrased that sentence a little. The difference between the phonemes /p/ and /b/ in Japanese. Why do academics stay as adjuncts for years rather than move around? This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' STR34-C. Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. "-D_FILE_OFFSET_BITS=64" "-Wall" "-Winvalid-pch" "-g" "-Wthread-safety" "-Wno-microsoft-enum-forward-reference" "-Wno-unused-function" "-Wno-sometimes-unini This example is noncompliant on an implementation where pointers are 64 bits and unsigned integers are 32 bits because the result of converting the 64-bit ptr cannot be represented in the 32-bit integer type. There exist two main syntaxes for generic type-casting: functional and c-like: 1 2 3 4 double x = 10.3; int y; y = int (x); // functional notation y = (int) x; // c-like cast notation The functionality of these generic forms of type-casting is enough for most needs with fundamental data types. Connect and share knowledge within a single location that is structured and easy to search. Java Type Casting. Note the difference between the type casting of a variable and type casting of a pointer. ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' Casting a pointer to void* and back is valid use of reinterpret_cast<>. If the source type is bool, the value false is converted to zero and the value true is converted to the value one of the destination type (note that if the destination type is int, this is an integer promotion, not an integer conversion). Bulk update symbol size units from mm to map units in rule-based symbology. Can Martian regolith be easily melted with microwaves? For integer casts in specific, using into() signals that . What is the point of Thrower's Bandolier? I personally upvoted this answer because by it's first line of text it helped me to understand the reason of this strange error message and what am I, poor idiot, doing :D. Not valid on Windows 64 - long is still 32-bit but pointers are 64-bit. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. tialized" "-Wno-format" "-Wno-incompatible-pointer-types" "-Werror" "-dM" "-U_MSC_VER" "-D_TIMESPEC_DEFINED" "-D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_SECURE_NO_WA The code ((void*)ptr + 1) does not work, because the compiler has no idea what size "void" is, and therefore doesn't know how many bytes to add. So the compiler is very picky here and the correct solution to make the code compile again and still let it show the exact same behavior like in Xcode 5.0 is to first cast to an integer type with a size that matches the one of a pointer and to then do a second cast to the int that we actually want: ids [i] = (int) (size_t)touch; Why did Ukraine abstain from the UNHRC vote on China? To learn more, see our tips on writing great answers. What video game is Charlie playing in Poker Face S01E07? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? I agree passing a dynamically allocated pointer is fine (and I think the best way). If you do this, you have the thread reference a value that (hopefully still) lives in some other thread. I need to convert the argument to an int for later use: The compiler (GCC version 4.2.4) returns the error: You can cast it to an intptr_t type. Apparently the clang version in Xcode 5.1 and above is more strict about potential 32bit vs. 64 bit incompatibilities in source code than older clang versions have been. Implicit Type Conversion is also known as 'automatic type conversion'. Don't do that. He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. This page has been accessed 1,655,678 times. pthread create managing values generated in function (in c), Establishing TCP socket connection between PHP client and C server on Ubuntu. Such a downcast makes no runtime checks to ensure that the object's runtime type is actually D, and may only be used safely if this precondition is guaranteed by other means, such as when implementing static polymorphism. SCAN_PUT(ATTR, NULL); This solution is in accordance with INT18-C. The problem just occur with Xcode 5.1. You can only do this if you use a synchronization primitive to ensure that there is no race condition. whether it was an actual problem is a different matter though. (int*)Pc = pa; After the execution of the above code all the three pointers, i.e., Pa, Pd, and Pc, point to the value 150. However even though their types are different, the address is going to be the same. Using printf with a pointer to float gives an error, Meaning of int (*) (int *) = 5 (or any integer value), Casting int to void* loses precision, and what is the solution in required cases, Acidity of alcohols and basicity of amines. No idea how it amassed 27 upvotes?! To be honest, I think, clang is too restrictive here. B programing language is a language based on basic combined programming or a BCPL, and it is the precursor of the C programming language. To avoid truncating your pointer, cast it to a type of identical size. You are right! Why do small African island nations perform better than African continental nations, considering democracy and human development? I am compiling this program in linux gcc compiler.. If the destination type is bool, this is a boolean conversion (see below). Do new devs get fired if they can't solve a certain bug? Put your define inside a bracket: without a problem. Create an account to follow your favorite communities and start taking part in conversations. Usually that means the pointer is allocated with. Using indicator constraint with two variables. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Instead of using a long cast, you should cast to size_t. I assumed that gcc makes a 65536 out of my define, but I was wrong. If your standard library (even if it is not C99) happens to provide these types - use them. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Press question mark to learn the rest of the keyboard shortcuts. There's no proper way to cast this to int in general case. Notifications. Don't do that. Actions. And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. So you know you can cast it back like this. You can fix this error by replacing this line of code. ncdu: What's going on with this second size column? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. The cast back to int * is not, though. How do I align things in the following tabular environment? @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. Just re-enforcing the old behavior of Xcode 5.0 and earlier versions, that already cut away parts of the address by casting it to int, won't introduce any new bugs and avoids the need to learn and understand lots of implementation-internal cocos code. Converting a pointer to an integer whose result cannot represented in the integer type is undefined behavior is C and prohibited in C++. Terrible solution. ", "? Whats the grammar of "For those whose stories they are"? I wish that you write those answer first than the explanation. To cast such pointers to 32-bit types and vice versa special functions are used: void * Handle64ToHandle ( const void * POINTER_64 h ) void * POINTER_64 HandleToHandle64 ( const void *h ) long HandleToLong ( const void *h ) unsigned long HandleToUlong ( const void *h )

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cast to void *' from smaller integer type 'int

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What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Get the address of a callback function to call dynamically in C++, error: call of overloaded function ambiguous, error: cast from to unsigned int loses precision [-fpermissive]. SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); Put your define inside a bracket: #define M_TABLE_SIZE (64*1024) Now, you can do: static const void* M_OFFSET = (void*) M_TABLE_SIZE; without a problem. @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. you can pass the int value as void pointer like (void *)&n where n is integer, and in the function accept void pointer as parameter like void foo (void *n); and finally inside the function convert void pointer to int like, int num = * (int *)n;. C++ how to get the address stored in a void pointer? Why is this sentence from The Great Gatsby grammatical? Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Once you manage to make this cast, then what?! This page was last modified on 12 February 2023, at 18:25. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. What is the purpose of this D-shaped ring at the base of the tongue on my hiking boots? But this code pass the normal variable .. Thanks for contributing an answer to Stack Overflow! - the incident has nothing to do with me; can I use this this way? ../lib/odp-util.c:5489:33: note: expanded from macro 'SCAN_PUT_ATTR' The problem is not with casting, but with the target type loosing half of the pointer. rev2023.3.3.43278. The following behavior-changing defect reports were applied retroactively to previously published C++ standards. I have the following function and when I compile it under VS.NET 2005, the following compile warnings show up: Warning1warning C4311: 'type cast' : pointer truncation from 'void *' to 'long'c:\temp\testone\lib\utils.c56Warning2warning C4312: 'type cast' : conversion from 'unsigned long' to 'void *' of greater sizec:\temp\testone\lib\utils.c56, Code Snippet If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. The main point is: a pointer has a platform dependent size. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @Dinesh: could you please 1) show us those. (int) pthread_self() 64int48intuintptr_t (unsigned int) SCAN_PUT_ATTR(key, ATTR, skey, FUNC); The correct answer is, if one does not mind losing data precision. what happens when we typecast normal variable to void* or any pointer variable? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Thanks. Using Kolmogorov complexity to measure difficulty of problems? How to use Slater Type Orbitals as a basis functions in matrix method correctly? Disconnect between goals and daily tasksIs it me, or the industry? Thanks for contributing an answer to Stack Overflow! What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. I recall there was a TreeNode(int) early on prior to 1.0 release I can't remember why I removed it, if I should felt it was easy enough to cast to (void*) or if it was because it created type inference conflict at the call site. you can just change architecture to support 32 bit compilation by all below in in Build Settings. Can I tell police to wait and call a lawyer when served with a search warrant? You are correct, but cocos actually only uses that address as a unique id. Floating-point conversions And, most of these will not even work on gcc4. So the compiler is very picky here and the correct solution to make the code compile again and still let it show the exact same behavior like in Xcode 5.0 is to first cast to an integer type with a size that matches the one of a pointer and to then do a second cast to the int that we actually want: I am using size_t here, because it is always having the same size as a pointer, no matter the platform. The dynamic_cast<>operator provides a way to check the actual type of a pointer to a polymorphic class. From the question I presume the OP does. A cast specifies a conversion from one type to another. Thanks for pointing that out. And in this context, it is very very very common to see programmers lazily type cast the. If you cast an int pointer int, you might get back a different integer. Connect and share knowledge within a single location that is structured and easy to search. If that happens soon after the call to pthread_create() then you have a race condition, because there's a chance that the thread will attempt to read x's value after it's life has ended, which invokes undefined behavior. Find centralized, trusted content and collaborate around the technologies you use most. (void *)i Error: cast to 'void *' from smaller integer type 'int'. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? This will get you a pointer from a 32 bit offset: A function pointer is incompatible to void* (and any other non function pointer). But I don't want to edit code in "EAGLView.mm" because it's a "library file". This is memory reinterpretation - a completely unacceptable way to do what the OP is trying to do. Pd = Pa; Similarly, Pc may be type cast to type int and assigned the value Pa. 1. should we also have a diagnostic for the (presumed) user error? use $(ARCHS_STANDARD_32_BIT) at Architecture instead of $(ARCHS_STANDARD). returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); What is the purpose of non-series Shimano components? The int data type is the primary integer data type in SQL Server. To learn more, see our tips on writing great answers. How to tell which packages are held back due to phased updates, Identify those arcade games from a 1983 Brazilian music video. You think by casting it here that you are avoiding the problem! So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. Just edited. If you are planning to use pthreads and you are planning to pass the pass function to pthread_create, you have to malloc/free the arguments you are planning to use (even if the threaded function just need a single int). Mutually exclusive execution using std::atomic? Replacing broken pins/legs on a DIP IC package, AC Op-amp integrator with DC Gain Control in LTspice. Typically, long or unsigned long is . Basically its a better version of (void *)i. The pointer doesn't actually point to anything, but it's the result of an earlier cast from an integer to a pointer (e.g. As Ferruccio said, int must be replaced with intptr_t to make the program meaningful. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? Find centralized, trusted content and collaborate around the technologies you use most. That could create all kinds of trouble. But I'm nitpicking .. The value of float variable is= 37.75. SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); The compiler issues the "cast from integer to pointer of different size" warning whenever the value of an integer is converted to a pointer, especially when the memory allocated to a pointer is smaller than the memory allocated to an integer data type. While working with Threads in C, I'm facing the warning, "warning: cast to pointer from integer of different size". What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Why is this sentence from The Great Gatsby grammatical? I don't see how anything bad can happen . Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? It generally takes place when in an expression more than one data type is present. On most platforms pointers and longs are the same size, but ints and pointers often are not the same size on 64bit platforms. The nature of simulating nature: A Q&A with IBM Quantum researcher Dr. Jamie We've added a "Necessary cookies only" option to the cookie consent popup. SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); reinterpret_cast is a type of casting operator used in C++. If the value is ever used as pointer again that will prove to be an extremely bad idea. that any valid pointer to void can be converted to this type, then To access the object value, use the * dereference operator: int * p; assert (p == null ); p = new int (5); assert (p != null ); assert (*p == 5); (*p)++; assert (*p == 6); If a pointer contains a null value, it is not pointing to a valid object. cast operators [edit] When an expression is used in the context where a value of a different type is expected, conversionmay occur: intn =1L;// expression 1L has type long, int is expectedn =2.1;// expression 2.1 has type double, int is expectedchar*p =malloc(10);// expression malloc(10) has type void*, char* is expected A sane compiler may throw a warning on lines like this but by no way it should throw an error, because this code is NOT wrong, it is just potentially error-prone, but can be perfectly valid. Remarks. 471,961 Members | 900 Online. Thanks for contributing an answer to Stack Overflow! ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] equal to the original pointer: First you are using a define, which is not a variable. How do I set, clear, and toggle a single bit? From that point on, you are dealing with 32 bits. privacy statement. Yesterday, I updated Xcode to the newest version (5.1 (5B130a)) to compatible with iOS 7.1. Does Counterspell prevent from any further spells being cast on a given turn? Does a summoned creature play immediately after being summoned by a ready action? If you write ((char*)ptr + 1), it will advance the pointer 1 byte, because a "char" is 1 byte. C/C++ , Cerror: cast to 'void *' from smaller integer type 'int'. ERROR: incompatible integer to pointer conversion assigning to 'string' (aka 'char *') from 'int', error: cast to 'string' (aka 'char *') from smaller integer type 'int' [-Werror,-Wint-to-pointer-cast], error: incompatible integer to pointer conversion assigning to 'string' (aka 'char *') from 'int' C, warning: initialization of 'unsigned char' from 'uint8_t *' {aka 'unsigned char *'} makes integer from pointer without a cast [-Wint-conversion], Minimising the environmental effects of my dyson brain. Why does setupterm terminate the program? When is casting void pointer needed in C? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. You cannot just cast the 32-bit variable to a pointer, because that pointer on a 64-bit machine is twice as long. Is it possible to create a concave light? Linear regulator thermal information missing in datasheet. In my case, I was using a 32-bit value that needed to be passed to an OpenGL function as a void * representing an offset into a buffer. I need to cast the int from the first function so that I can use it as an argument for the second function. Why does Mister Mxyzptlk need to have a weakness in the comics? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. How Intuit democratizes AI development across teams through reusability. However the actual code in question contains an explicit c-style cast to int. XCode 5.1 is change all architecture to 64 bit. Even if you are compiling your program for a 32-bit computer, you should fix your code to remove these warnings, to ensure your code is easily portable to 64-bit. This forum has migrated to Microsoft Q&A. static_cast on the other hand should deny your stripping away the const qualifier. If you convert (void*) to (long) no precision is lost, then by assigning the (long) to an (int), it properly truncates the number to fit. Replacing broken pins/legs on a DIP IC package, How to handle a hobby that makes income in US. Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. x is a local variable and its lifetime ends as soon as control leaves the scope it was defined in. The problem was there before, you just are being notified of it. Since gcc compiles that you are performing arithmetic between void* and an int (1024). Taking the above declarations of A, D, ch of the . So you could do this: Note: As sbi points out this would require a change on the OP call to create the thread. B language was designed to develop . If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . The most general answer is - in no way. void* -> integer -> void* rather than integer -> void* -> integer. For the remaining integral types, the result is the value of the enum if it can be represented by the target type and unspecified otherwise. The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. You may declare a const int variable and cast its reference to the void*. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. C99 defines the types "intptr_t" and "uintptr_t" which do . ^~~~~~~~~~~~~~~~~~~ Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? If the object expression refers or points to is actually a base class subobject of an object of type D, the result refers to the enclosing object of type D. Otherwise, the behavior is undefined: When the target type is bool (possibly cv-qualified), the result is false if the original value is zero and true for all other values. Yeah, the tutorial is doing it wrong. It is easier to understand and write than any other assembly language. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. If this is the data to a thread procedure, then you quite commonly want to pass by value. Passing arguments to pthread_create - invalid conversion from void(*)() to void(*)(void*). Thus as a result it may be less error prone to generate a pointer dynamcially and use that. Returns a value of type new-type. Casting arguments inside the function is a lot safer. Is pthread_join a must when using pthread in linux? long guarantees a pointer size on Linux on any machine. I have looked around and can't seem to find any information on how to do this. Noncompliant Code Example (memset())For historical reasons, certain C Standard functions accept an argument of type int and convert it to either unsigned char or plain char. The OP wanted to convert a pointer value to a int value, instead, most the answers, one way or the other, tried to wrongly convert the content of arg points to to a int value. Bulk update symbol size units from mm to map units in rule-based symbology. Getting Command /bin/sh failed with exit code 65 Error with Xcode 5.1 . byte -> short -> char -> int -> long -> float -> double. If you call your thread creation function like this, then the void* arriving inside of myFcn has the value of the int you put into it. The preprocessor will replace your code by this: This is unlikely what you are trying to do. Before I update Xcode, my project still can build and run normally with all devices. In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. Not the answer you're looking for? I think the solution 3> should be the correct one. how to cascade 2d int array to 2d void pointer array? My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. Cast characters to unsigned char before converting to larger integer sizes Created by Robert Seacord, last modified by Jill Britton on Oct 03, 2022 Signed character data must be converted to unsigned char before being assigned or converted to a larger signed type. There's no proper way to cast this to int in general case. Click to see the query in the CodeQL repository. 7.1 New Cast Operations The C++ standard defines new cast operations that provide finer control than previous cast operations. And in the function you get the value of the pointer by using the dereference operator *: Please read why glib provide macros for this kind of conversions, there's no need to repeat the text here. @jackdoe: It's a waste of human life to write code that "you may need in the future". error: cast from pointer to smaller type 'unsigned int' loses information. If the original pointer value represents an address of a byte in memory that does not satisfy the alignment requirement of the target type, then the resulting pointer value is unspecified. Hence there is no loss in data. But, sure, in that specific case you can pass a local variable address, type casting integer to void* [duplicate]. p-util.c.obj "-c" ../lib/odp-util.c All float types are to be converted to double. The subreddit for the C programming language, Press J to jump to the feed. If the original type is a void *, converting to an int may lose date on platforms where sizeof(void *) != sizeof(int) (which is true of LP64 programming model). The nature of simulating nature: A Q&A with IBM Quantum researcher Dr. Jamie We've added a "Necessary cookies only" option to the cookie consent popup. A cast is a way of explicitly informing the compiler that you intend to make the conversion and that you are aware that data loss might occur, or the cast may fail at run time. Making statements based on opinion; back them up with references or personal experience. How to get the error message from the error code returned by GetLastError()? ^~~~~~~~~~~~~~~~~~~~~ Don't pass your int as a void*, pass a int* to your int, so you can cast the void* to an int* and copy the dereferenced pointer to your int. By clicking Sign up for GitHub, you agree to our terms of service and 1. A missing cast in the new fast > enumeration code. Based on the design of this function, which modification is right. Keep in mind that thrArg should exist till the myFcn() uses it. Well occasionally send you account related emails. "-I.." "-Iinclude\openflow" "-I..\include\openflow" "-Iinclude\openvswitch" "-I..\include\openvsw then converted back to pointer to void, and the result will compare The result is the same as implicit conversion from the enum's underlying type to the destination type. . Making statements based on opinion; back them up with references or personal experience. Find centralized, trusted content and collaborate around the technologies you use most. I am an entry level C programmer. If the value in a pointer is cast to a different type and it does not have the correct alignment for the new type, the behavior is undefined. Evaluate integer expressions in a larger size before comparing or assigning to that size.Note that (time_+t)-1 also complies with INT31-C-EX3. Offline ImPer Westermark over 11 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. Not the answer you're looking for? How do I check if a string represents a number (float or int)? There are ways to prevent this: pass a dynamic allocated argument if your not the passing thread is not static or if your argument is a local variable, otherwise there is no issue. Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. Use returnPtr[j] = (void *) ((long)ptr + i); ). What does casting to void* does when passing arguments to variadic functions? What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? @Shahbaz you could but I will not suggest to a C newbie to use globals. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. SQL Server does not automatically promote . The best way is, if one can, do not do such casting, instead, if the same memory address has to be shared for pointer and int (e.g. Please note that the error I am receiving is "cast to smaller integer type 'int' from 'string' (aka 'char *')" referencing line of code: while (isalpha(residents[i].name) == 0). rev2023.3.3.43278. Find centralized, trusted content and collaborate around the technologies you use most. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. @DavidHeffernan I rephrased that sentence a little. The difference between the phonemes /p/ and /b/ in Japanese. Why do academics stay as adjuncts for years rather than move around? This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' STR34-C. Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. "-D_FILE_OFFSET_BITS=64" "-Wall" "-Winvalid-pch" "-g" "-Wthread-safety" "-Wno-microsoft-enum-forward-reference" "-Wno-unused-function" "-Wno-sometimes-unini This example is noncompliant on an implementation where pointers are 64 bits and unsigned integers are 32 bits because the result of converting the 64-bit ptr cannot be represented in the 32-bit integer type. There exist two main syntaxes for generic type-casting: functional and c-like: 1 2 3 4 double x = 10.3; int y; y = int (x); // functional notation y = (int) x; // c-like cast notation The functionality of these generic forms of type-casting is enough for most needs with fundamental data types. Connect and share knowledge within a single location that is structured and easy to search. Java Type Casting. Note the difference between the type casting of a variable and type casting of a pointer. ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' Casting a pointer to void* and back is valid use of reinterpret_cast<>. If the source type is bool, the value false is converted to zero and the value true is converted to the value one of the destination type (note that if the destination type is int, this is an integer promotion, not an integer conversion). Bulk update symbol size units from mm to map units in rule-based symbology. Can Martian regolith be easily melted with microwaves? For integer casts in specific, using into() signals that . What is the point of Thrower's Bandolier? I personally upvoted this answer because by it's first line of text it helped me to understand the reason of this strange error message and what am I, poor idiot, doing :D. Not valid on Windows 64 - long is still 32-bit but pointers are 64-bit. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. tialized" "-Wno-format" "-Wno-incompatible-pointer-types" "-Werror" "-dM" "-U_MSC_VER" "-D_TIMESPEC_DEFINED" "-D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_SECURE_NO_WA The code ((void*)ptr + 1) does not work, because the compiler has no idea what size "void" is, and therefore doesn't know how many bytes to add. So the compiler is very picky here and the correct solution to make the code compile again and still let it show the exact same behavior like in Xcode 5.0 is to first cast to an integer type with a size that matches the one of a pointer and to then do a second cast to the int that we actually want: ids [i] = (int) (size_t)touch; Why did Ukraine abstain from the UNHRC vote on China? To learn more, see our tips on writing great answers. What video game is Charlie playing in Poker Face S01E07? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? I agree passing a dynamically allocated pointer is fine (and I think the best way). If you do this, you have the thread reference a value that (hopefully still) lives in some other thread. I need to convert the argument to an int for later use: The compiler (GCC version 4.2.4) returns the error: You can cast it to an intptr_t type. Apparently the clang version in Xcode 5.1 and above is more strict about potential 32bit vs. 64 bit incompatibilities in source code than older clang versions have been. Implicit Type Conversion is also known as 'automatic type conversion'. Don't do that. He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. This page has been accessed 1,655,678 times. pthread create managing values generated in function (in c), Establishing TCP socket connection between PHP client and C server on Ubuntu. Such a downcast makes no runtime checks to ensure that the object's runtime type is actually D, and may only be used safely if this precondition is guaranteed by other means, such as when implementing static polymorphism. SCAN_PUT(ATTR, NULL); This solution is in accordance with INT18-C. The problem just occur with Xcode 5.1. You can only do this if you use a synchronization primitive to ensure that there is no race condition. whether it was an actual problem is a different matter though. (int*)Pc = pa; After the execution of the above code all the three pointers, i.e., Pa, Pd, and Pc, point to the value 150. However even though their types are different, the address is going to be the same. Using printf with a pointer to float gives an error, Meaning of int (*) (int *) = 5 (or any integer value), Casting int to void* loses precision, and what is the solution in required cases, Acidity of alcohols and basicity of amines. No idea how it amassed 27 upvotes?! To be honest, I think, clang is too restrictive here. B programing language is a language based on basic combined programming or a BCPL, and it is the precursor of the C programming language. To avoid truncating your pointer, cast it to a type of identical size. You are right! Why do small African island nations perform better than African continental nations, considering democracy and human development? I am compiling this program in linux gcc compiler.. If the destination type is bool, this is a boolean conversion (see below). Do new devs get fired if they can't solve a certain bug? Put your define inside a bracket: without a problem. Create an account to follow your favorite communities and start taking part in conversations. Usually that means the pointer is allocated with. Using indicator constraint with two variables. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Instead of using a long cast, you should cast to size_t. I assumed that gcc makes a 65536 out of my define, but I was wrong. If your standard library (even if it is not C99) happens to provide these types - use them. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Press question mark to learn the rest of the keyboard shortcuts. There's no proper way to cast this to int in general case. Notifications. Don't do that. Actions. And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. So you know you can cast it back like this. You can fix this error by replacing this line of code. ncdu: What's going on with this second size column? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. The cast back to int * is not, though. How do I align things in the following tabular environment? @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. Just re-enforcing the old behavior of Xcode 5.0 and earlier versions, that already cut away parts of the address by casting it to int, won't introduce any new bugs and avoids the need to learn and understand lots of implementation-internal cocos code. Converting a pointer to an integer whose result cannot represented in the integer type is undefined behavior is C and prohibited in C++. Terrible solution. ", "? Whats the grammar of "For those whose stories they are"? I wish that you write those answer first than the explanation. To cast such pointers to 32-bit types and vice versa special functions are used: void * Handle64ToHandle ( const void * POINTER_64 h ) void * POINTER_64 HandleToHandle64 ( const void *h ) long HandleToLong ( const void *h ) unsigned long HandleToUlong ( const void *h ) Sister Forever House Address, How Much Weight Can A 2x4 Stud Support Horizontally, Articles C

cast to void *' from smaller integer type 'intpercentage of deaths caused by cyberbullying

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