cast to void *' from smaller integer type 'int Is pthread_join a must when using pthread in linux? */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j;
This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. The preprocessor will replace your code by this: This is unlikely what you are trying to do. 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. (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. How can this new ban on drag possibly be considered constitutional? Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. Connect and share knowledge within a single location that is structured and easy to search. This answer is incorrect for the reasons that have already been mentioned in the comment of, Error "Cast from pointer to smaller type 'int' loses information" in EAGLView.mm when update Xcode to 5.1 (5B130a), http://en.wikipedia.org/wiki/64-bit_computing#64-bit_data_models, http://stackoverflow.com/questions/18913906/xcode-5-and-ios-7-architecture-and-valid-architectures, How Intuit democratizes AI development across teams through reusability. Thanks for contributing an answer to Stack Overflow! Cast Operations - Oracle [] 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). 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. Visit Microsoft Q&A to post new questions. Why is this sentence from The Great Gatsby grammatical? ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Hence there is no loss in data. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. This is an old C callback mechanism so you can't change that. In such condition type conversion (type promotion) takes place to avoid loss of data. 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 [.]) rev2023.3.3.43278. Implementing From will result in the Into implementation but not vice-versa. } SCAN_END_SINGLE(ATTR) The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. then converted back to pointer to void, and the result will compare Even though what you say regarding the lifetime of the object is true, integral types are too limited for a generic API. linux c-pthreads: problem with local variables. 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. If this is the data to a thread procedure, then you quite commonly want to pass by value. I need to cast the int from the first function so that I can use it as an argument for the second function. The dynamic_cast<>operator provides a way to check the actual type of a pointer to a polymorphic class. The problem is not with casting, but with the target type loosing half of the pointer. However the actual code in question contains an explicit c-style cast to int. 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. @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. Type casting is when you assign a value of one primitive data type to another type. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. You are just making it bigger by tricking the compiler and the ABI. 471,961 Members | 900 Online. Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. 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. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. I'm only guessing here, but I think what you are supposed to do is actually pass the address of the variable to the function. Thanks for pointing that out. The most general answer is - in no way. Wrong. to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj (i.e. For the Nozomi from Shinagawa to Osaka, say on a Saturday afternoon, would tickets/seats typically be available - or would you need to book? Casting int to void* : r/C_Programming - reddit What does casting to void* does when passing arguments to variadic functions? - the incident has nothing to do with me; can I use this this way? Whats the grammar of "For those whose stories they are"? So you could do this: Note: As sbi points out this would require a change on the OP call to create the thread. 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. void* -> integer -> void* rather than integer -> void* -> integer. Please tell me error: cast from 'void*' to 'int' loses precision, How Intuit democratizes AI development across teams through reusability. It is done by the compiler on its own, without any external trigger from the user. When is casting void pointer needed in C? Sign up for a free GitHub account to open an issue and contact its maintainers and the community. Use of Void pointers in C programming language vegan) just to try it, does this inconvenience the caterers and staff? sound/soc/codecs/tlv320aic32x4.c:1202:18: warning: cast to smaller For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. Asking for help, clarification, or responding to other answers. Yesterday, I updated Xcode to the newest version (5.1 (5B130a)) to compatible with iOS 7.1. 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. A cast converts an object or value from one type to another. 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. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? this way you won't get any warning. I don't see how anything bad can happen . Casting type void to uint8_t - Arduino Forum rev2023.3.3.43278. 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. This page was last modified on 12 February 2023, at 18:25. To avoid truncating your pointer, cast it to a type of identical size. What is the purpose of non-series Shimano components? What does it mean to convert int to void* or vice versa? To learn more, see our tips on writing great answers. Mutually exclusive execution using std::atomic? What happens if you typecast as unsigned first? Your first example is risky because you have to be very careful about the object lifetimes. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? */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
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