cast to void *' from smaller integer type 'int
@DavidHeffernan I rephrased that sentence a little. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. From the question I presume the OP does. I agree passing a dynamically allocated pointer is fine (and I think the best way). For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. Don't do that. The mapping in pointer<->integer casts is implementation defined, but the intent was that if the pointer type is large enough and isn't forcefully aligned (, But that's different. Why did Ukraine abstain from the UNHRC vote on China? Projects. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. You think by casting it here that you are avoiding the problem! Do new devs get fired if they can't solve a certain bug? Such pointers can be stored in 32-bit data types (for instance, int, DWORD). itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" The main point is: a pointer has a platform dependent size. 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. 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. The proper way is to cast it to another pointer type. This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. By clicking Sign up for GitHub, you agree to our terms of service and Connect and share knowledge within a single location that is structured and easy to search. INT31-C. Ensure that integer conversions do not result in lost or That could create all kinds of trouble. Where does this (supposedly) Gibson quote come from? 1. (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. 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. Why do small African island nations perform better than African continental nations, considering democracy and human development? 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. cast to void *' from smaller integer type 'int Otherwise, if the original pointer value points to an object a, and there is an object b of the . A void pointer can be really useful if the programmer is not sure about the data type of data inputted by the end user. How to correctly type cast (void*)? - social.msdn.microsoft.com Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? But I'm nitpicking .. To learn more, see our tips on writing great answers. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? 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". What is the point of Thrower's Bandolier? that any valid pointer to void can be converted to this type, then 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. Find centralized, trusted content and collaborate around the technologies you use most. c - How to cast an integer to void pointer? - Stack Overflow Casting and type conversions - C# Programming Guide Mutually exclusive execution using std::atomic? How do I align things in the following tabular environment? you can just change architecture to support 32 bit compilation by all below in in Build Settings. But then you need to cast your arguments inside your thread function which is quite unsafe cf. Using Kolmogorov complexity to measure difficulty of problems? Casting type void to uint8_t - Arduino Forum Can Martian regolith be easily melted with microwaves? I have a two functions, one that returns an int, and one that takes a const void* as an argument. Making statements based on opinion; back them up with references or personal experience. Only the following conversions can be done with static_cast, except when such conversions would cast away constness or volatility. The preprocessor will replace your code by this: This is unlikely what you are trying to do. We have to pass address of the variable to the function because in function definition argument is pointer variable. Asking for help, clarification, or responding to other answers. If the value is ever used as pointer again that will prove to be an extremely bad idea. clang11 report error: cast to smaller integer type #82 - GitHub "I think what you should do is actually pass the address of the variable to the function" Not necessarily. You are getting warnings due to casting a void* to a type of a different size. Why does setupterm terminate the program? Java Type Casting. Whats the grammar of "For those whose stories they are"? ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. Even though what you say regarding the lifetime of the object is true, integral types are too limited for a generic API. Making statements based on opinion; back them up with references or personal experience. This will only compile if the destination type is long enough. 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. 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]. Where does this (supposedly) Gibson quote come from? So reinterpret_cast has casted it to long type and then static_cast safely casts long to int, if you are ready do truncte the data. It is commonly called a pointer to T and its type is T*. This is an old C callback mechanism so you can't change that. 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. rev2023.3.3.43278. But the problem has still happened. linux c-pthreads: problem with local variables. Clang warnings for an invalid casting? - The FreeBSD Forums Connect and share knowledge within a single location that is structured and easy to search. The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. Mutually exclusive execution using std::atomic? Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. Is pthread_join a must when using pthread in linux? Cast Operations - Oracle 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. In such a case the programmer can use a void pointer to point to the location of the unknown data type. This is memory reinterpretation - a completely unacceptable way to do what the OP is trying to do. Converts between types using a combination of implicit and user-defined conversions. Thanks for contributing an answer to Stack Overflow! to the original pointer: The following type designates an unsigned integer type with the Basically its a better version of (void *)i. Yesterday, I updated Xcode to the newest version (5.1 (5B130a)) to compatible with iOS 7.1. This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. There is no "correct" way to store a 64-bit pointer in an 32-bit integer. A cast specifies a conversion from one type to another. You are correct, but cocos actually only uses that address as a unique id. } SCAN_END_SINGLE(ATTR) What does it mean to convert int to void* or vice versa? The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS, AC Op-amp integrator with DC Gain Control in LTspice, Identify those arcade games from a 1983 Brazilian music video. 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. 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). 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; In Java, there are two types of casting: Widening Casting (automatically) - converting a smaller type to a larger type size. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. converted back to pointer to void, and the result will compare equal ), Styling contours by colour and by line thickness in QGIS. C - Type Casting - tutorialspoint.com I have looked around and can't seem to find any information on how to do this. 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. "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' But gcc always give me a warning, that i cannot cast an int to a void*. Visit Microsoft Q&A to post new questions. You use the address-of operator & to do that. It was derived from the BCPL, and the name of the b language is possibly from the BCPL contraction. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. What you do here is undefined behavior, and undefined behavior of very practical sort. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ "clang" "-Ilib\libopenvswitch.a.p" "-Ilib" "-I..\lib" "-I." 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). Then i can continue compiling. ^~~~~~~~~~~~~~~~~~~ . How Intuit democratizes AI development across teams through reusability. ^~~~~~~~~~~~~~~~~~~~ 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). @Shahbaz you could but I will not suggest to a C newbie to use globals. Implicit Type Conversion is also known as 'automatic type conversion'. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Why is there a voltage on my HDMI and coaxial cables? casting from int to void* and back to int. a cast of which the programmer should be aware of what (s)he is doing.
What I am saying is that it would be safer to use new(5) rather than 5 and deal with it appropriately at the other end. The subreddit for the C programming language, Press J to jump to the feed. Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. As with all cast expressions, the result is: Two objects a and b are pointer-interconvertible if: static_cast may also be used to disambiguate function overloads by performing a function-to-pointer conversion to specific type, as in. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? whether it was an actual problem is a different matter though. void* -> integer -> void* rather than integer -> void* -> integer. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? Casting int to void* loses precision, and what is the solution in required cases, c++: cast from "const variable*" to "uint32" loses precision, Recovering from a blunder I made while emailing a professor, Relation between transaction data and transaction id. Bulk update symbol size units from mm to map units in rule-based symbology. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 4. Type Conversions - C in a Nutshell [Book] - O'Reilly Online Learning this way you won't get any warning. Can we typecast void into int? - Quora Number Type Cast | Qt Forum *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 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 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 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. I don't see how anything bad can happen . Mutually exclusive execution using std::atomic? Cast a smaller integer to a larger integer - community - The Rust Why does Mister Mxyzptlk need to have a weakness in the comics? The only alternative is really to take time and fix all 64-bit code issues, of which there may be some non-trivial issues. rev2023.3.3.43278. The following program casts a double to an int. All float types are to be converted to double. In this case, casting the pointer back to an integer is meaningless, because . Does Counterspell prevent from any further spells being cast on a given turn? rev2023.3.3.43278. 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). [] ExplanatioUnlike static_cast, but like const_cast, the reinterpret_cast expression does not compile to any CPU instructions (except when converting between integers and pointers or on obscure architectures where pointer representation depends on its type). ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, You should be doing int x = *((int *)arg); You are casting from void * to int that is why you get the warning. How can this new ban on drag possibly be considered constitutional? The most general answer is - in no way. How to use Slater Type Orbitals as a basis functions in matrix method correctly? Making statements based on opinion; back them up with references or personal experience. So you could do this: Note: As sbi points out this would require a change on the OP call to create the thread. Type Casting in C Language with Examples - Dot Net Tutorials The text was updated successfully, but these errors were encountered: You signed in with another tab or window. If your standard library (even if it is not C99) happens to provide these types - use them. Use #include
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