cast to void *' from smaller integer type 'int cast to void *' from smaller integer type 'int

How to get the error message from the error code returned by GetLastError()? You use the address-of operator & to do that int x = 10; void *pointer = &x; And in the function you get the value of the pointer by using the dereference operator *: int y = * ( (int *) pointer); Share Improve this answer Follow edited Apr 15, 2013 at 13:58 answered Apr 15, 2013 at 13:53 Some programmer dude 394k 35 393 602 1 @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. However the actual code in question contains an explicit c-style cast to int. clang11 report error: cast to smaller integer type #82 - GitHub Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, "what happen when typcating normal variable to void* or any pointer variable?" 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. Mutually exclusive execution using std::atomic? Basically its a better version of (void *)i. How do I count the number of sentences in C using ". Find centralized, trusted content and collaborate around the technologies you use most. How to correctly cast a pointer to int in a 64-bit application? Use #include to define it. 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. Connect and share knowledge within a single location that is structured and easy to search. Why is there a voltage on my HDMI and coaxial cables? I would create a structure and pass that as void* to pthread_create. 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. For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. Why is there a voltage on my HDMI and coaxial cables? Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? } SCAN_END_SINGLE(ATTR) Implicit conversions - cppreference.com Narrowing Casting (manually) - converting a larger type to a . The difference between the phonemes /p/ and /b/ in Japanese. How to use Slater Type Orbitals as a basis functions in matrix method correctly? for (i=0, j=0; jint, bigint, smallint, and tinyint (Transact-SQL) - SQL Server To avoid truncating your pointer, cast it to a type of identical size. @BlueMoon Thanks a lot! */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. For the Nozomi from Shinagawa to Osaka, say on a Saturday afternoon, would tickets/seats typically be available - or would you need to book? 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. 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. Properly casting a `void*` to an integer in C++ 24,193 Solution 1 I think using intptr_t is the correct intermediate here, since it's guaranteed to be large enough to contain the integral value of the void*, and once I have an integer value I can then truncate it without causing the compiler to complain. Why did Ukraine abstain from the UNHRC vote on China? In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. Why is there a voltage on my HDMI and coaxial cables? "-I.." "-Iinclude\openflow" "-I..\include\openflow" "-Iinclude\openvswitch" "-I..\include\openvsw BUT converting a pointer to void* and back again is well supported (everywhere). 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. Why do small African island nations perform better than African continental nations, considering democracy and human development? ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Type Casting in C Language with Examples - Dot Net Tutorials This returns the first 32 bits of the pointer which may be the top or the bottom depending on big versus little endian, as comment #2 said. The subreddit for the C programming language, Press J to jump to the feed. Find centralized, trusted content and collaborate around the technologies you use most. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Implicit conversions - cppreference.com Now, what happens when I run it with the thread sanitizer? Notifications. Have a question about this project? He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. This forum has migrated to Microsoft Q&A. 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. Since the 'size' argument for your function is the number of bytes each element in the array needs, I think casting the pointerto (char*) is appropriate. ../lib/odp-util.c:5489:33: note: expanded from macro 'SCAN_PUT_ATTR' The main point is: a pointer has a platform dependent size. 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. arrays - I get the error: "cast to smaller integer type 'int' from This will get you a pointer from a 32 bit offset: A function pointer is incompatible to void* (and any other non function pointer). C++ how to get the address stored in a void pointer? Casting a pointer to void* and back is valid use of reinterpret_cast<>. If the value is ever used as pointer again that will prove to be an extremely bad idea. If you preorder a special airline meal (e.g. How can this new ban on drag possibly be considered constitutional? I have a two functions, one that returns an int, and one that takes a const void* as an argument. This allows you to reinterpret the void * as an int. How to use Slater Type Orbitals as a basis functions in matrix method correctly? to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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). On all of them int is 32bit, not 16bit. 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 [.]) Is it suspicious or odd to stand by the gate of a GA airport watching the planes? The int data type is the primary integer data type in SQL Server. The problem just occur with Xcode 5.1. But this code pass the normal variable .. This is not a conversion at all. How do I force make/GCC to show me the commands? ", "? Thanks for contributing an answer to Stack Overflow! Cerror: cast to 'void *' from smaller integer type 'int' I'm using cocos2d-x-2.2.2. how to cascade 2d int array to 2d void pointer array? Using indicator constraint with two variables. The correct answer is, if one does not mind losing data precision. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); whether it was an actual problem is a different matter though. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. what does it mean to convert int to void* or vice versa? reinterpret_cast is a type of casting operator used in C++. Casting arguments inside the function is a lot safer. 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). You need to cast the void* pointer to a char* pointer - and then dereference that char* pointer to give you the char that it points to! How can this new ban on drag possibly be considered constitutional? Acidity of alcohols and basicity of amines. Casting type void to uint8_t - Arduino Forum warning C4311: 'type cast': pointer truncation from 'void *' to 'long' in ECPG test files. Asking for help, clarification, or responding to other answers. 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. The value of float variable is= 37.75. In 64-bit programs, the size of the pointer is 64 bits, and cannot be put into the int type, which remains 32-bit in almost all systems. The preprocessor will replace your code by this: This is unlikely what you are trying to do. 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. error: cast from 'void*' to 'int' loses precision - Stack Overflow (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. What is the purpose of non-series Shimano components? 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). -1, Uggh. Thanks for contributing an answer to Stack Overflow! Otherwise, if the original pointer value points to an object a, and there is an object b of the . From what I read about casting in the C11 standard, my feeling is, that it is arguable to emit a warning on an explicit conversion. Casting int to void* : r/C_Programming - reddit 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. Already on GitHub? Why is this sentence from The Great Gatsby grammatical? Cast Operations - Oracle You are correct, but cocos actually only uses that address as a unique id. 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 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;. Pull requests. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? But I don't want to edit code in "EAGLView.mm" because it's a "library file". Why does setupterm terminate the program? Click to see the query in the CodeQL repository. If the function had the correct signature you would not need to cast it explicitly. Disconnect between goals and daily tasksIs it me, or the industry? SCAN_PUT(ATTR, NULL); You think by casting it here that you are avoiding the problem! this question. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? RNINGS" "-D_CRT_SECURE_NO_DEPRECATE" -MD -MQ lib/libopenvswitch.a.p/odp-util.c.obj -MF "lib\libopenvswitch.a.p\odp-util.c.obj.d" -o lib/libopenvswitch.a.p/od @Martin York: No, it doesn't depend on endiannness. How to use Slater Type Orbitals as a basis functions in matrix method correctly? 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. Create an account to follow your favorite communities and start taking part in conversations. Cast a smaller integer to a larger integer - community - The Rust 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. this way you won't get any warning. Making statements based on opinion; back them up with references or personal experience. The reinterpret_cast makes the int the size of a pointer and the warning will stop. To learn more, see our tips on writing great answers. Taking the above declarations of A, D, ch of the . Does a summoned creature play immediately after being summoned by a ready action? The problem was there before, you just are being notified of it. 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. If you really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. But the problem has still happened. Pd = Pa; Similarly, Pc may be type cast to type int and assigned the value Pa. 1. Thanks. What is the purpose of non-series Shimano components? 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 What is "cast from integer to pointer of different size" warning? In the first example, the variable c1 of the char type is converted to a temporary variable of the int type, because the second operand in the division operation, the constant 2, is of the higher type int. What is the point of Thrower's Bandolier? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. You can use a 64 bits integer instead howerver I usually use a function with the right prototype and I cast the function type : @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. Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? static const void* M_OFFSET = (void*)64*1024; Since gcc compiles that you are performing arithmetic between void* and an int ( 1024 ). And when assigning to a void pointer, all type information is lost. Put your define inside a bracket: without a problem. unsigned long call_fn = (unsigned long)FUNC; You can use any other pointer, or you can use (size_t), which is 64 bits. that any valid pointer to void can be converted to this type, then pthread create managing values generated in function (in c), Establishing TCP socket connection between PHP client and C server on Ubuntu. If you do this, you have the thread reference a value that (hopefully still) lives in some other thread. C/C++ , Cerror: cast to 'void *' from smaller integer type 'int'. If you cast an int pointer int, you might get back a different integer. Typically, long or unsigned long is . Netdev Archive on lore.kernel.org help / color / mirror / Atom feed * [mst-vhost:vhost 5/52] drivers/block/virtio_blk.c:539:21: warning: assignment to 'void *' from . So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. I'm trying to create a void* from an int. Casting Pointers - IBM I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . Thanks Jonathan, I was thinking about my answer in another thread: AraK is correct, passing integers a pointers are not necessarily interchangeable. You could use this code, and it would do the same thing as casting ptr to (char*). (void *)i Error: cast to 'void *' from smaller integer type 'int'. I assumed that gcc makes a 65536 out of my define, but I was wrong. Type Casting Of Pointers in C - Computer Notes Just edited. 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. Java Type Casting (With Examples) - Programiz By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. ^~~~~~~~~~~~~~~~~~~~~ cast to 'void *' from smaller integer type 'int' windows meson: cast to smaller integer type 'unsigned long' from 'void Is it possible to create a concave light? The cast back to int * is not, though. and how to print the thread id of 2d array argument? Connect and share knowledge within a single location that is structured and easy to search. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). windows meson: cast to smaller integer type 'unsigned long' from 'void *'. Identify those arcade games from a 1983 Brazilian music video, Relation between transaction data and transaction id, The difference between the phonemes /p/ and /b/ in Japanese. Clang warnings for an invalid casting? - The FreeBSD Forums Since gcc compiles that you are performing arithmetic between void* and an int (1024). XCode 5.1 is change all architecture to 64 bit. I have a function with prototype void* myFcn(void* arg) which is used as the starting point for a pthread. The calculated expression consists of two operations. There's probably little you can do except look or hope for a fixed 2.x version or upgrade to 3.x (I would assume it's 64-bit safe but this is just a guess, do research this issue before you upgrade). Just want to point out that the purpose of threads is, +1 absolutely true, but if you take you time to write struct {}, you can save a lot of troubles in the future when you want to receive/send more data then just an int. c - How to cast an integer to void pointer? - Stack Overflow I understood, but that would introduce dynamic memory and ugly lifetime issues (an object allocated by one thread must be freed by some other) - all just to pass an. Hence there is no loss in data. I'm new to coding and am trying to implement a simple program on my own, that prompts the user the number of residents in an apt complex, the prompts the user to enter the names and apt numbers of each resident. Not the answer you're looking for? The result is implementation-defined and typically yields the numeric address of the byte in memory that the pointer pointers to. Type casting is when you assign a value of one primitive data type to another type. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). Terrible solution. STR34-C. Cast characters to unsigned char before converting to larger rev2023.3.3.43278. 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. My code is all over the place now but I appreciate you all helping me on my journey to mastery! Java Type Casting - W3Schools Making statements based on opinion; back them up with references or personal experience. I'm unfamiliar with XCode, but the solution should be something like follows: Most of the "solutions" above can lose part of the pointer address when casting to a smaller type. 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. A void pointer can be really useful if the programmer is not sure about the data type of data inputted by the end user. A nit: in your version, the cast to void * is unnecessary. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. What does casting to void* does when passing arguments to variadic functions? ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] [Solved] Properly casting a `void*` to an integer in C++ C / C++ Forums on Bytes. with ids being an array of ints and touch being a pointer. Connect and share knowledge within a single location that is structured and easy to search. (i.e. 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. Replacing broken pins/legs on a DIP IC package, How to handle a hobby that makes income in US. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? Not the answer you're looking for? I need to cast the int from the first function so that I can use it as an argument for the second function. 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. How Intuit democratizes AI development across teams through reusability. Can I tell police to wait and call a lawyer when served with a search warrant? Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Bulk update symbol size units from mm to map units in rule-based symbology. a cast of which the programmer should be aware of what (s)he is doing. void* to an array - C++ Forum - cplusplus.com Well it does this because you are converting a 64 bits pointer to an 32 bits integer so you loose information. C99 defines the types "intptr_t" and "uintptr_t" which do . Don't do that. casting from int to void* and back to int - C / C++ Use returnPtr[j] = (void *) ((long)ptr + i); ). Keep in mind that thrArg should exist till the myFcn() uses it. C99 standard library provides intptr_t and uintptr_t typedefs, which are supposed to be used whenever the need to perform such a cast comes about. 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. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? You should perform type conversion based on 64bit build system because the type "int" supports only -32768 ~ 32768. That's probably going to be true for most platforms you will ever encounter, but it's not a guarantee; it's implementation-dependent. To learn more, see our tips on writing great answers. Typecasting - Data Types - Language Basics - MQL4 Reference Compile error on Android ARM Issue #163 cisco/ChezScheme Next, when doing pointer arithmetic, the addition operation will use the pointer's type to determine how many bytes to add to it when incrementing it. What is the point of Thrower's Bandolier? INT36-C. Converting a pointer to integer or integer to pointer Bulk update symbol size units from mm to map units in rule-based symbology. to the original pointer: The following type designates an unsigned integer type with the How do I work around the GCC "error: cast from SourceLocation* to int loses precision" error when compiling cmockery.c? long guarantees a pointer size on Linux on any machine. This explicit cast clearly tells the compiler "Shut up, I know that this code does not look correct, but I do know what I am doing". Sign up for a free GitHub account to open an issue and contact its maintainers and the community. Even though what you say regarding the lifetime of the object is true, integral types are too limited for a generic API. How to notate a grace note at the start of a bar with lilypond? If you are going to pass the address you typically need to exert some more control over the lifetime of the object. Api says this is how i should create thread: So if I want to pass an int what I think I should do is: The second example assumes that a pointer is wide enough to store an int. Bulk update symbol size units from mm to map units in rule-based symbology. You are right! 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. This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. rev2023.3.3.43278. Implementing From will result in the Into implementation but not vice-versa. If you preorder a special airline meal (e.g. property that any valid pointer to void can be converted to this type, The proper way is to cast it to another pointer type.