^~~~~~~~~~~~~~~~~~~ Pull requests. To learn more, see our tips on writing great answers. 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. *sound/soc/codecs/tlv320aic32x4.c:1202:18: warning: cast to smaller integer type 'enum aic32x4_type' from 'void *' @ 2022-04-22 9:48 kernel test robot 0 siblings, 0 . You are getting warnings due to casting a void* to a type of a different size. 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. Please help me compile Chez Scheme. If your code has the chance to ever be ported to some platform where this doesn't hold, this won't work. (void *)i Error: 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. If the destination type is bool, this is a boolean conversion (see below). INT36-C. Converting a pointer to integer or integer to pointer error: comparison between pointer and integer ('int' and 'string' (aka 'char *')), CS50 Caesar program is working but check50 says it isn't. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You could use this code, and it would do the same thing as casting ptr to (char*). Star 675. Find centralized, trusted content and collaborate around the technologies you use most. @Shahbaz you could but I will not suggest to a C newbie to use globals. Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? But then you need to cast your arguments inside your thread function which is quite unsafe cf. B Programming Language | What is the History and Concept? You may declare a const int variable and cast its reference to the void*. Windows has 32 bit long only on 64 bit as well. what happens when we typecast normal variable to void* or any pointer variable? Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? 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? Why do academics stay as adjuncts for years rather than move around? On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. Implementation-dependent. The following program casts a double to an int. equal to the original pointer: First you are using a define, which is not a variable. Offline ImPer Westermark over 11 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. pthread create managing values generated in function (in c), Establishing TCP socket connection between PHP client and C server on Ubuntu. Whats the grammar of "For those whose stories they are"? 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. What is the correct method to cast an int to a void*? I cannot reverse my upvote of user384706's answer, but it's wrong. Cast a smaller integer to a larger integer - community - The Rust Not the answer you're looking for? c - Cast int to void* - Stack Overflow 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. In C (int)b is called an explicit conversion, i.e. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? 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). I need to cast the int from the first function so that I can use it as an argument for the second function. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. Projects. [PATCH] platform/x86: hp-wmi: Fix cast to smaller integer type warning Click to see the query in the CodeQL repository. rev2023.3.3.43278. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, "what happen when typcating normal variable to void* or any pointer variable?" Why is this sentence from The Great Gatsby grammatical? Half your pointer will be garbage. to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj It modifies >> Wconversion-real.c, Wconversion-real-integer.c and pr35635.c to be more >> specific > > If the patch passes existing tests, I'd be inclined to leave them > tests alone and add new ones that are specific to what this patch > changes. You need to pass an actual pointer. Remembering to delete the pointer after use so that we don't leak. ", "? What is the purpose of this D-shaped ring at the base of the tongue on my hiking boots? What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. But gcc always give me a warning, that i cannot cast an int to a void*. vegan) just to try it, does this inconvenience the caterers and staff? A cast specifies a conversion from one type to another. ^~~~~~~~~~~~~~~~~~~~~ ncdu: What's going on with this second size column? 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). This is not a conversion at all. On all of them int is 32bit, not 16bit. Create an account to follow your favorite communities and start taking part in conversations. Infact I know several systems where that does not hold. You can convert the values from one type to another explicitly using the cast operator as follows (type_name) expression This is a fine way to pass integers to new pthreads, if that is what you need. Not the answer you're looking for? Converts between types using a combination of implicit and user-defined conversions. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. void* to an array - C++ Forum - cplusplus.com Implicit conversions - cppreference.com It is purely a compile-time directive which instructs the compiler to treat expression as if it had . Yeah, the tutorial is doing it wrong. Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. Now, what happens when I run it with the thread sanitizer? Fork 63. And in this context, it is very very very common to see programmers lazily type cast the. actually no, as int my be a smaller type than a pointer ;-) But, of course with int64_t it works fine. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. casting from int to void* and back to int - C / C++ [that could be a TODO - not to delay solving the ICE]. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. what does it mean to convert int to void* or vice versa? What video game is Charlie playing in Poker Face S01E07? Does Counterspell prevent from any further spells being cast on a given turn? This forum has migrated to Microsoft Q&A. "After the incident", I started to be more careful not to trip over things. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' 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. Why is there a voltage on my HDMI and coaxial cables? Can Martian regolith be easily melted with microwaves? The cast back to int * is not, though. Asking for help, clarification, or responding to other answers. This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. If you do this, you have the thread reference a value that (hopefully still) lives in some other thread. 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. (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. 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 What is "cast from integer to pointer of different size" warning? Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Note:You might receive a runtime exception if the pointer contains a value unsuitable for the context. In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. The int data type is the primary integer data type in SQL Server. Cast unsigned char (uint8 *) pointer to unsigned long (uint32 *) pointer warning C4311: 'type cast': pointer truncation from 'void *' to 'long' in ECPG test files. Thanks for contributing an answer to Stack Overflow! Returns a value of type new-type. windows meson: cast to smaller integer type 'unsigned long' from 'void In Java, there are two types of casting: Widening Casting (automatically) - converting a smaller type to a larger type size. There is absolutely not gurantee that sizeof(int) <= sizeof(void*). clang11 report error: cast to smaller integer type #82 - GitHub 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 [.]) Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. A void pointer can be really useful if the programmer is not sure about the data type of data inputted by the end user. 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). Before I update Xcode, my project still can build and run normally with all devices. Using an integer address (like &x) is probably wrong, indeed each modification you will execute on x will affect the pass behaviour. for (i=0, j=0; jNumber Type Cast | Qt Forum What does casting to void* does when passing arguments to variadic functions? ), Styling contours by colour and by line thickness in QGIS. As for the stack, I've written a few libraries using pthreds, thus I don't agree that what you describe "is quite often the case". How to correctly cast a pointer to int in a 64-bit application? what does it mean to convert int to void* or vice versa? Typically, long or unsigned long is . What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Xcode 5 and iOS 7: Architecture and Valid architectures, xcode build error: Semantic issue cast from pointer to smaller type 'int' loses information, Issues in handling touches on subviews(uiviews) in UIScrollView, Architecture linking error after Xcode 5.1 upgrade, iOS 7.1 gives error after updating to Xcode 5.1, Linker error in Xcode 5.1 with cocos2d-x 3 beta 2. 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. Casting type void to uint8_t - Arduino Forum STR34-C. Cast characters to unsigned char before converting to larger LLNL's tutorial is bad and they should feel bad. Don't do that. Instead of using a long cast, you should cast to size_t. C++ how to get the address stored in a void pointer? 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. Use of Void pointers in C programming language Thanks for contributing an answer to Stack Overflow! Converting a void* to an int is non-portable way that may work or may not! You can only do this if you use a synchronization primitive to ensure that there is no race condition. (i.e. Casting arguments inside the function is a lot safer. this way you won't get any warning. For example, the main thread could wait for all of the other threads to end before terminating. If you write ((char*)ptr + 1), it will advance the pointer 1 byte, because a "char" is 1 byte. The dynamic_cast<>operator provides a way to check the actual type of a pointer to a polymorphic class. Clang warnings for an invalid casting? - The FreeBSD Forums This page has been accessed 1,655,678 times. Why do small African island nations perform better than African continental nations, considering democracy and human development? Remarks. See also this documentation.. From and Into are generally intended to be lossless, infalliable conversions.as on the other hand can discard data and lead to bugs in some situations, for example casting a u64 to a usize may truncate the value on a 32-bit host. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. INT31-C. Ensure that integer conversions do not result in lost or (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. Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. If you are going to pass the address you typically need to exert some more control over the lifetime of the object. This solution is in accordance with INT18-C. Where does this (supposedly) Gibson quote come from? Is pthread_join a must when using pthread in linux? void* -> integer -> void* rather than integer -> void* -> integer. A long long would not work for 32bit systems and a long would not work for 64 bit Windows (while 64bit Unix and Unix-like systems like OS X use the LP64 data model, in which a long is 64bit, 64bit Windows uses the LLP64 data model, in which a long has a size of 32bit (http://en.wikipedia.org/wiki/64-bit_computing#64-bit_data_models)). Note the difference between the type casting of a variable and type casting of a pointer. static_cast conversion - cppreference.com But the problem has still happened. To avoid truncating your pointer, cast it to a type of identical size. While working with Threads in C, I'm facing the warning, "warning: cast to pointer from integer of different size". From the question I presume the OP does. 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. B programing language is a language based on basic combined programming or a BCPL, and it is the precursor of the C programming language. 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. ncdu: What's going on with this second size column? ../lib/odp-util.c:5489:33: note: expanded from macro 'SCAN_PUT_ATTR' 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. Notifications. cast to void *' from smaller integer type 'int ^~~~~~~~~~~~~~~~~~~~~ Casting a pointer to void* and back is valid use of reinterpret_cast<>. this way I convert an int to a void* which is much better than converting a void* to an int. Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. vegan) just to try it, does this inconvenience the caterers and staff? But I'm nitpicking .. Passing arguments to pthread_create - invalid conversion from void(*)() to void(*)(void*). The problem is not with casting, but with the target type loosing half of the pointer. . Connect and share knowledge within a single location that is structured and easy to search. Yeah, the tutorial is doing it wrong. Your first example is risky because you have to be very careful about the object lifetimes. And then assign it to the double variable. Java Type Casting. 1. To be honest, I think, clang is too restrictive here. int, bigint, smallint, and tinyint (Transact-SQL) - SQL Server - the incident has nothing to do with me; can I use this this way? 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. All float types are to be converted to double. this question. Why is there a voltage on my HDMI and coaxial cables? As Ferruccio said, int must be replaced with intptr_t to make the program meaningful. I wish that you write those answer first than the explanation. 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; To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? How to use Slater Type Orbitals as a basis functions in matrix method correctly? reinterpret_cast conversion - cppreference.com Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @Dinesh: could you please 1) show us those. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? This is why you got Error 1 C2036, from your post. @DavidHeffernan, sane thread APIs wouldn't send integral data to the thread procedures, they would send pointers. Keep in mind that thrArg should exist till the myFcn() uses it. Making statements based on opinion; back them up with references or personal experience. } SCAN_END_SINGLE(ATTR) The most general answer is - in no way. Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. Is it possible to create a concave light? On many systems, an 8-bit unsigned int can be stored at any address while an unsigned 32-bit int must be aligned on an address that is a multiple of 4. 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 The point is (probably) that the value passed to the thread is an integer value, not really a 'void *'. The correct answer is, if one does not mind losing data precision. Again, all of the answers above missed the point badly. 10) A prvalue of type pointer to void (possibly cv-qualified) can be converted to pointer to any object type. 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. lexborisov Modest Public. Functions return bigint only if the parameter expression is a bigint data type. 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. Yesterday, I updated Xcode to the newest version (5.1 (5B130a)) to compatible with iOS 7.1. Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Type conversions - cplusplus.com 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. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Does ZnSO4 + H2 at high pressure reverses to Zn + H2SO4? This is what the second warning is telling you. On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. Narrowing Casting (manually) - converting a larger type to a . Well it does this because you are converting a 64 bits pointer to an 32 bits integer so you loose information. ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] should we also have a diagnostic for the (presumed) user error? This allows you to reinterpret the void * as an int. Why did Ukraine abstain from the UNHRC vote on China? p-util.c.obj "-c" ../lib/odp-util.c @BlueMoon Thanks a lot!