cast to void *' from smaller integer type 'int

what happens when we typecast normal variable to void* or any pointer variable? windows meson: cast to smaller integer type 'unsigned long' from 'void Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. 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. "-D_FILE_OFFSET_BITS=64" "-Wall" "-Winvalid-pch" "-g" "-Wthread-safety" "-Wno-microsoft-enum-forward-reference" "-Wno-unused-function" "-Wno-sometimes-unini Therefore it is perfectly valid for the compiler to throw an error for a line like. Connect and share knowledge within a single location that is structured and easy to search. This is what the second warning is telling you. Star 675. The point is (probably) that the value passed to the thread is an integer value, not really a 'void *'. 471,961 Members | 900 Online. For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. @BlueMoon Thanks a lot! Implicit conversions - cppreference.com a cast of which the programmer should be aware of what (s)he is doing. All float types are to be converted to double. Cast a smaller integer to a larger integer - community - The Rust The subreddit for the C programming language, Press J to jump to the feed. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? However, you are also casting the result of this operation to (void*). On most platforms pointers and longs are the same size, but ints and pointers often are not the same size on 64bit platforms. However the actual code in question contains an explicit c-style cast to int. If the value is ever used as pointer again that will prove to be an extremely bad idea. Types - D Programming Language To avoid truncating your pointer, cast it to a type of identical size. Number Type Cast | Qt Forum Thanks for contributing an answer to Stack Overflow! No idea how it amassed 27 upvotes?! You should perform type conversion based on 64bit build system because the type "int" supports only -32768 ~ 32768. and how to print the thread id of 2d array argument? Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). Sign in Such pointers can be stored in 32-bit data types (for instance, int, DWORD). By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. And when assigning to a void pointer, all type information is lost. Asking for help, clarification, or responding to other answers. Even though what you say regarding the lifetime of the object is true, integral types are too limited for a generic API. Pull requests. tialized" "-Wno-format" "-Wno-incompatible-pointer-types" "-Werror" "-dM" "-U_MSC_VER" "-D_TIMESPEC_DEFINED" "-D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_SECURE_NO_WA Does Counterspell prevent from any further spells being cast on a given turn? The proper way is to cast it to another pointer type. Mutually exclusive execution using std::atomic? 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. If you preorder a special airline meal (e.g. LLNL's tutorial is bad and they should feel bad. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. How create a simple program using threads in C? I'm trying to learn pthreads and thing that keeps bugging me is how do i really pass argument to the function. If you are going to pass the address you typically need to exert some more control over the lifetime of the object. C / C++ Forums on Bytes. But assuming that it is, as long as the caller and the callee agree, you can do that sort of thing. actually no, as int my be a smaller type than a pointer ;-) But, of course with int64_t it works fine. what does it mean to convert int to void* or vice versa? Disconnect between goals and daily tasksIs it me, or the industry? 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). 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. Before I update Xcode, my project still can build and run normally with all devices. 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. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. Find centralized, trusted content and collaborate around the technologies you use most. ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] How do I align things in the following tabular environment? @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Is pthread_join a must when using pthread in linux? I cannot reverse my upvote of user384706's answer, but it's wrong. should we also have a diagnostic for the (presumed) user error? It is easier to understand and write than any other assembly language. If you need to keep the returned address, just keep it as void*. @Martin York: No, it doesn't depend on endiannness. Or, they are all wrong. Casting and type conversions - C# Programming Guide Why does Mister Mxyzptlk need to have a weakness in the comics? 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. 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. A void pointer can be really useful if the programmer is not sure about the data type of data inputted by the end user. 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. How to Cast a void* ponter to a char without a warning? Use #include to define it. If any, how can the original function works without errors if we just ignore the warning. Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? How to use Slater Type Orbitals as a basis functions in matrix method correctly? How to correctly cast a pointer to int in a 64-bit application? What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, "what happen when typcating normal variable to void* or any pointer variable?" 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). A cast specifies a conversion from one type to another. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? then converted back to pointer to void, and the result will compare ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' void* -> integer -> void* rather than integer -> void* -> integer. B Programming Language | What is the History and Concept? return ((void **) returnPtr);} /* Matrix() */. Do new devs get fired if they can't solve a certain bug? Note that it's not guaranteed that casting an, Generally this kind of type casting does not lead to any concern as long as the addresses are encoded using the same length as the "variable type" (. 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 If you preorder a special airline meal (e.g. Then I build my project, I get the error "Cast from pointer to smaller type 'int' loses information" in EAGLView.mm file (line 408) when 64-bit simulators (e.g. The problem just occur with Xcode 5.1. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? Mutually exclusive execution using std::atomic? In simple example code like this it's very easy to convince yourself that there's no problem, but in more elaborate real-world scenarios it's very easy to make this mistake inadvertently. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? 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;. 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. Why is there a voltage on my HDMI and coaxial cables? This is not even remotely "the correct answer". ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Offline ImPer Westermark over 11 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. Thanks Jonathan, I was thinking about my answer in another thread: AraK is correct, passing integers a pointers are not necessarily interchangeable. As Ferruccio said, int must be replaced with intptr_t to make the program meaningful. I'm using cocos2d-x-2.2.2. The dynamic_cast<>operator provides a way to check the actual type of a pointer to a polymorphic class. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ There's no proper way to cast this to int in general case. 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". By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. But this code pass the normal variable ..

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