It is purely a compile-time directive which instructs the compiler to treat expression as if it had . Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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 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;. If the destination type is bool, this is a boolean conversion (see below). If your code has the chance to ever be ported to some platform where this doesn't hold, this won't work. 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; Infact I know several systems where that does not hold. 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 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. Once you manage to make this cast, then what?! Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Using an integer address (like &x) is probably wrong, indeed each modification you will execute on x will affect the pass behaviour. 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. ^~~~~~~~~~~~~~~~~~~~ To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Safe downcast may be done with dynamic_cast. ^~~~~~~~~~~~~~~~~~~ There's no proper way to cast this to int in general case. 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. Already on GitHub? If you cast an int pointer int, you might get back a different integer. This example is noncompliant on an implementation where pointers are 64 bits and unsigned integers are 32 bits because the result of converting the 64-bit ptr cannot be represented in the 32-bit integer type. How Intuit democratizes AI development across teams through reusability. The correct answer is, if one does not mind losing data precision. For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. In a 64bit build a pointer is 64bit (contrary to a 32bit build, where it is 32bit), while an int is 32bit, so this assignment stores a 64bit value in a 32bit storage, which may result in a loss of information. I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. No sense in writing a few dozen lines of extra code just to get a bunch of numbered threads. Connect and share knowledge within a single location that is structured and easy to search. this way you won't get any warning. The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. You are getting warnings due to casting a void* to a type of a different size. Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Getting Command /bin/sh failed with exit code 65 Error with Xcode 5.1 . Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Setting a buffer of char* with intermediate casting to int*. Windows has 32 bit long only on 64 bit as well. 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. Or, they are all wrong. The following program casts a double to an int. FAILED: lib/libopenvswitch.a.p/odp-util.c.obj That's probably going to be true for most platforms you will ever encounter, but it's not a guarantee; it's implementation-dependent. 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. Your first example is risky because you have to be very careful about the object lifetimes. Taking the above declarations of A, D, ch of the . If you call your thread creation function like this, then the void* arriving inside of myFcn has the value of the int you put into it. Projects. I am an entry level C programmer. What is the point of Thrower's Bandolier? Is it possible to create a concave light? linux c-pthreads: problem with local variables. The point is (probably) that the value passed to the thread is an integer value, not really a 'void *'. You are getting warnings due to casting a void* to a type of a different size. byte -> short -> char -> int -> long -> float -> double. Most answers just try to extract 32 useless bits out of the argument. reinterpret_cast<void *>(42)). 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. 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. This solution is in accordance with INT18-C. Difficulties with estimation of epsilon-delta limit proof. For example, the main thread could wait for all of the other threads to end before terminating. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. ", "!"? An object pointer (including void*) or function pointer can be converted to an integer type using reinterpret_cast. ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' Find centralized, trusted content and collaborate around the technologies you use most. The problem just occur with Xcode 5.1. Can Martian regolith be easily melted with microwaves? privacy statement. What is the correct method to cast an int to a void*? 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. There is absolutely not gurantee that sizeof(int) <= sizeof(void*). ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function. . Does ZnSO4 + H2 at high pressure reverses to Zn + H2SO4? Floating-point conversions This is an old C callback mechanism so you can't change that. rev2023.3.3.43278. Casting a pointer to void* and back is valid use of reinterpret_cast<>. 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. Put your define inside a bracket: without a problem. Thanks. cast to 'double *' from smaller integer type 'unsigned int' The C compiler is gcc, clang version 3.9.1, target aarch64--linux-android, thread model posix. It is commonly called a pointer to T and its type is T*. Such a downcast makes no runtime checks to ensure that the object's runtime type is actually D, and may only be used safely if this precondition is guaranteed by other means, such as when implementing static polymorphism. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, "what happen when typcating normal variable to void* or any pointer variable?" XCode 5.1 is change all architecture to 64 bit. rev2023.3.3.43278. *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 . The bigint data type is intended for use when integer values might exceed the range that is supported by the int data type.. bigint fits between smallmoney and int in the data type precedence chart.. Well occasionally send you account related emails. 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. Do new devs get fired if they can't solve a certain bug? You need to pass an actual pointer. Converting a pointer to an integer whose result cannot represented in the integer type is undefined behavior is C and prohibited in C++. The difference between the phonemes /p/ and /b/ in Japanese. To learn more, see our tips on writing great answers. ../lib/odp-util.c:5601:9: note: expanded from macro 'SCAN_PUT' Don't do that. SCAN_PUT(ATTR, NULL); Making statements based on opinion; back them up with references or personal experience. 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. Making statements based on opinion; back them up with references or personal experience. 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. Recovering from a blunder I made while emailing a professor. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. Asking for help, clarification, or responding to other answers. Why did Ukraine abstain from the UNHRC vote on China? 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! Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). You should perform type conversion based on 64bit build system because the type "int" supports only -32768 ~ 32768. 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. You can use any other pointer, or you can use (size_t), which is 64 bits. Please help me compile Chez Scheme. The main point is: a pointer has a platform dependent size. 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.
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