How Intuit democratizes AI development across teams through reusability. While working with Threads in C, I'm facing the warning, "warning: cast to pointer from integer of different size". 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. Acidity of alcohols and basicity of amines. You may declare a const int variable and cast its reference to the void*. Casting type void to uint8_t - Arduino Forum Basically its a better version of (void *)i. I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. B language was designed to develop . Cast Operations - Oracle property that any valid pointer to void can be converted to this type, I have looked around and can't seem to find any information on how to do this. The subreddit for the C programming language, Press J to jump to the feed. Your first example is risky because you have to be very careful about the object lifetimes. returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); Asking for help, clarification, or responding to other answers. To be honest, I think, clang is too restrictive here. C - Type Casting - tutorialspoint.com Casting type int to const void* - C / C++ All character types are to be converted to an integer. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, error: cast from void* to int loses precision, cast to pointer from integer of different size, pthread code. B Programming Language | What is the History and Concept? There's no proper way to cast this to int in general case. However, I believe that even if the define was for the "65536", it would not be what @kaetzacoatl wanted. In a 64bit build a pointer is 64bit (contrary to a 32bit build, where it is 32bit), while an int is 32bit, so this assignment stores a 64bit value in a 32bit storage, which may result in a loss of information. casting from int to void* and back to int. How to use Slater Type Orbitals as a basis functions in matrix method correctly? @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. The int data type is the primary integer data type in SQL Server. Why does setupterm terminate the program? Here is some piece of code where that error occur: /cocos2d-x-2.2.2/cocos2dx/platform/ios/EAGLView.mm:408:18: Cast from pointer to smaller type 'int' loses information. Type conversions - cplusplus.com Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); for (i=0, j=0; j returnPtr[j] = (void *) (ptr + i); // <<< Compile Errors, Error1error C2036: 'void *' : unknown sizec:\temp\testone\lib\utils.c57, 2> returnPtr[j] = (void *) ((long*)ptr + i); // <<< No compile errors, 3> returnPtr[j] = (void *) ((char*)ptr + i); // <<< No compile errors. How to correctly cast a pointer to int in a 64-bit application? ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? a is of type int[4], which can be implicitly cast to int* (ie, a pointer to an int) &a is of type int(*)[4] (ie: a pointer to an array of 4 ints). : iPhone Retina 4-inch 64-bit) is selected. You use the address-of operator & to do that. unsigned long call_fn = (unsigned long)FUNC; Difficulties with estimation of epsilon-delta limit proof. For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. Remembering to delete the pointer after use so that we don't leak. C++ Tutorial => Conversion between pointer and integer Therefore it is perfectly valid for the compiler to throw an error for a line like. If the destination type is bool, this is a boolean conversion (see below). Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. How to tell which packages are held back due to phased updates, Identify those arcade games from a 1983 Brazilian music video. for (i=0, j=0; jCan we typecast void into int? - Quora Asking for help, clarification, or responding to other answers. Offline ImPer Westermark over 11 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. The only exception is exotic systems with the SILP64 data model, where the size of int is also 64 bits. @Xax: Here's a fixed version, without the race condition: gist.github.com/depp/241d6f839b799042c409, gist.github.com/depp/3f04508a88a114734195, How Intuit democratizes AI development across teams through reusability. c - type casting integer to void* - Stack Overflow Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @Dinesh: could you please 1) show us those. 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_PUT_ATTR(mask, ATTR, smask, FUNC); ^~~~~~~~~~~~~~~~~~~~ Since all pointers on 64-bit Windows are 64 bits, you are growing the data size from 32 bits backto 64 bits. You can only do this if you use a synchronization primitive to ensure that there is no race condition. Why does flowing off the end of a non-void function without returning a value not produce a compiler error? Referring to N1570 7.20.1.4/p1 (Integer types capable of holding object pointers): The following type designates a signed integer type with the property 4. Type Conversions - C in a Nutshell [Book] - O'Reilly Online Learning Why do small African island nations perform better than African continental nations, considering democracy and human development? (int) pthread_self() 64int48intuintptr_t (unsigned int) This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. Otherwise, if the original pointer value points to an object a, and there is an object b of the . @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. Getting Command /bin/sh failed with exit code 65 Error with Xcode 5.1 . A missing cast in the new fast > enumeration code. 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. 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; you can just change architecture to support 32 bit compilation by all below in in Build Settings. Fork 63. 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. Thanks for contributing an answer to Stack Overflow! 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. 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. I get the error: "cast to smaller integer type 'int' from 'string' (aka 'char *')" referencing line of code: while (isalpha(residents[i].name) == 0), How Intuit democratizes AI development across teams through reusability. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' Replacing broken pins/legs on a DIP IC package, AC Op-amp integrator with DC Gain Control in LTspice. int, bigint, smallint, and tinyint (Transact-SQL) - SQL Server Type casting is when you assign a value of one primitive data type to another type. Identify those arcade games from a 1983 Brazilian music video. (Also, check out how it prints "5" twice), passing a unique pointer to each thread wont race, and you can get/save any kind of information in the th struct. When is casting void pointer needed in C? Recovering from a blunder I made while emailing a professor. From the question I presume the OP does. SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); If it's anything like cocos2d-iphone v2.x and just based on this slice of code in a core class I wager it's safe to say that cocos2d-x 2.x also is not compatible with 64 bit code, and you can expect all kinds of issues (not just compile-time but also runtime). The correct answer is, if one does not mind losing data precision. 1. 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. The following program casts a double to an int. Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul Terrible solution. For the second example you can make sure that sizeof (int) <= sizeof (void *) by using a static_assert -- this way at least you'll get a notice about it. (i.e. eg. Why did Ukraine abstain from the UNHRC vote on China? But then you need to cast your arguments inside your thread function which is quite unsafe cf. My code is all over the place now but I appreciate you all helping me on my journey to mastery! Using indicator constraint with two variables. cast to void *' from smaller integer type 'int Narrowing Casting (manually) - converting a larger type to a . Disconnect between goals and daily tasksIs it me, or the industry? [Solved] Properly casting a `void*` to an integer in C++ Why is this sentence from The Great Gatsby grammatical? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. In the best case this will give the same results as the original code, with no advantages, but in the worst case it will fail in multiple catastrophic ways (type punning, endianness, less efficient, etc. arrays - I get the error: "cast to smaller integer type 'int' from 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. Making statements based on opinion; back them up with references or personal experience. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Thanks for contributing an answer to Stack Overflow! Anw, the project still build and run normally when i use Xcode 5.0 with iOS 7.0. return ((void **) returnPtr);} /* Matrix() */. Any expression can be cast to type void (which means that the result of the expression is ignored), but it's not legal to cast an expression of type void to type int not least because the result of such a cast wouldn't make any sense. itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function. How do I work around the GCC "error: cast from SourceLocation* to int loses precision" error when compiling cmockery.c? To avoid truncating your pointer, cast it to a type of identical size. this question. There's no proper way to cast this to int in general case. What video game is Charlie playing in Poker Face S01E07? Therefore, you need to change it to long long instead of long in windows for 64 bits. Don't do that. What is the correct method to cast an int to a void*? 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. (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. Asking for help, clarification, or responding to other answers. So you could do this: Note: As sbi points out this would require a change on the OP call to create the thread. 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. What you do here is undefined behavior, and undefined behavior of very practical sort. Wrong. 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. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. But, sure, in that specific case you can pass a local variable address, type casting integer to void* [duplicate]. The main point is: a pointer has a platform dependent size. Hence there is no loss in data. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Again, all of the answers above missed the point badly. The preprocessor will replace your code by this: This is unlikely what you are trying to do. vegan) just to try it, does this inconvenience the caterers and staff? 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;. And then assign it to the double variable. If the function had the correct signature you would not need to cast it explicitly. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. rev2023.3.3.43278. And when assigning to a void pointer, all type information is lost. I think the solution 3> should be the correct one. Half your pointer will be garbage. How do I align things in the following tabular environment? A pointer converted to an integer of sufficient size and back to the same pointer type is guaranteed to have its original value, otherwise the resulting pointer cannot be dereferenced safely ( the round-trip conversion in the opposite direction is not guaranteed [.])