Does melting sea ices rises global sea level? How to correctly cast a pointer to int in a 64-bit application? error: cast from 'void*' to 'int' loses precision - Stack Overflow 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. ^~~~~~~~~~~~~~~~~~~~ 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. It is easier to understand and write than any other assembly language. However, you are also casting the result of this operation to (void*). What video game is Charlie playing in Poker Face S01E07? Why is there a voltage on my HDMI and coaxial cables? If you preorder a special airline meal (e.g. You can use any other pointer, or you can use (size_t), which is 64 bits. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Have a question about this project? Or, they are all wrong. If you preorder a special airline meal (e.g. ^~~~~~~~~~~~~~~~~~~~~ ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You can also convert values from one type to another explicitly using the cast operator (see Chapter 5 ): ( type_name) expression In the following example, the cast operator causes the division of one integer variable by another to be performed as a floating-point operation: int sum = 22, count = 5; double mean = (double)sum / count; To subscribe to this RSS feed, copy and paste this URL into your RSS reader. The text was updated successfully, but these errors were encountered: Star 675. 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. iphone - Error "Cast from pointer to smaller type 'int' loses property that any valid pointer to void can be converted to this type, How to get the error message from the error code returned by GetLastError()? I have looked around and can't seem to find any information on how to do this. I'm trying to create a void* from an int. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. If the destination type is bool, this is a boolean conversion (see below). Well occasionally send you account related emails. 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. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? The preprocessor will replace your code by this: This is unlikely what you are trying to do. Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. To learn more, see our tips on writing great answers. Passing arguments to pthread_create - invalid conversion from void(*)() to void(*)(void*). cast to void *' from smaller integer type 'int Create an account to follow your favorite communities and start taking part in conversations. 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. But, sure, in that specific case you can pass a local variable address, type casting integer to void* [duplicate]. C++ Tutorial => Conversion between pointer and integer Anw, the project still build and run normally when i use Xcode 5.0 with iOS 7.0. For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. This is what the second warning is telling you. 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 Connect and share knowledge within a single location that is structured and easy to search. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Re: [PATCH, PR 53001] Re: Patch to split out new warning flag for Implicit Type Conversion in C with Examples - GeeksforGeeks Referring to N1570 7.20.1.4/p1 (Integer types capable of holding object pointers): The following type designates a signed integer type with the property You cannot just cast the 32-bit variable to a pointer, because that pointer on a 64-bit machine is twice as long. The int data type is the primary integer data type in SQL Server. for saving RAM), use union, and make sure, if the mem address is treated as an int only if you know it was last set as an int. even though the compiler doesn't know you only ever pass myFcn to pthread_create in conjunction with an integer. 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. You can only do this if you use a synchronization primitive to ensure that there is no race condition. [Solved] Error "Cast from pointer to smaller type 'int' | 9to5Answer SCAN_PUT_ATTR(key, ATTR, skey, FUNC); C - Type Casting - tutorialspoint.com 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. You need to pass an actual pointer. The difference between a and &a is the type. How do I work around the GCC "error: cast from SourceLocation* to int loses precision" error when compiling cmockery.c? 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". 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;. Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. If any, how can the original function works without errors if we just ignore the warning. STR34-C. Cast characters to unsigned char before converting to larger And then assign it to the double variable. byte -> short -> char -> int -> long -> float -> double. This is not a conversion at all. How can this new ban on drag possibly be considered constitutional? What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. this question. Types - D Programming Language A missing cast in the new fast > enumeration code. And when assigning to a void pointer, all type information is lost. Find centralized, trusted content and collaborate around the technologies you use most. You can convert the values from one type to another explicitly using the cast operator as follows (type_name) expression It solved my problem too. Casting type void to uint8_t - Arduino Forum Not the answer you're looking for? 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; If you do this, you have the thread reference a value that (hopefully still) lives in some other thread. 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. Asking for help, clarification, or responding to other answers. You just need to suppress the warning, and this will do it: This may offend your sensibilities, but it's very short and has no race conditions (as you'd have if you used &i). The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. Thanks Jonathan, I was thinking about my answer in another thread: AraK is correct, passing integers a pointers are not necessarily interchangeable. You think by casting it here that you are avoiding the problem! Notifications. The text was updated successfully, but these errors were encountered: You signed in with another tab or window. The proper way is to cast it to another pointer type. clang warnings in v1.42 Issue #265 ocornut/imgui GitHub In the first example, the variable c1 of the char type is converted to a temporary variable of the int type, because the second operand in the division operation, the constant 2, is of the higher type int. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? 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. To learn more, see our tips on writing great answers. rev2023.3.3.43278. Casting an open pointer to other pointer types and casting other pointer types to an open pointer does not result in a compile time error. Clang warnings for an invalid casting? - The FreeBSD Forums this way I convert an int to a void* which is much better than converting a void* to an int. Visit Microsoft Q&A to post new questions. 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. It generally takes place when in an expression more than one data type is present. [that could be a TODO - not to delay solving the ICE]. Converting a void* to an int is non-portable way that may work or may not! INT36-C. Converting a pointer to integer or integer to pointer SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); You use the address-of operator & to do that. Can Martian regolith be easily melted with microwaves? casting from int to void* and back to int. 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. The result is implementation-defined and typically yields the numeric address of the byte in memory that the pointer pointers to. itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" How to use Slater Type Orbitals as a basis functions in matrix method correctly? Cerror: cast to 'void *' from smaller integer type 'int' unsigned long call_fn = (unsigned long)FUNC; @jackdoe: It's a waste of human life to write code that "you may need in the future". converted back to pointer to void, and the result will compare equal However even though their types are different, the address is going to be the same. Most answers just try to extract 32 useless bits out of the argument. Again, all of the answers above missed the point badly. Maybe you can try this too. Casting int to void* : r/C_Programming - reddit By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Java Type Casting (With Examples) - Programiz To access the object value, use the * dereference operator: int * p; assert (p == null ); p = new int (5); assert (p != null ); assert (*p == 5); (*p)++; assert (*p == 6); If a pointer contains a null value, it is not pointing to a valid object. The problem was there before, you just are being notified of it. And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. Can I tell police to wait and call a lawyer when served with a search warrant? GitHub. Note the difference between the type casting of a variable and type casting of a pointer. But assuming that it is, as long as the caller and the callee agree, you can do that sort of thing. 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. ^~~~~~~~~~~~~~~~~~~ You are right! This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. ../lib/odp-util.c:5601:9: note: expanded from macro 'SCAN_PUT' Yeah, the tutorial is doing it wrong. A nit: in your version, the cast to void * is unnecessary. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. 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. Find centralized, trusted content and collaborate around the technologies you use most. How to notate a grace note at the start of a bar with lilypond? 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. So you know you can cast it back like this. For the Nozomi from Shinagawa to Osaka, say on a Saturday afternoon, would tickets/seats typically be available - or would you need to book? 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. 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. 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. An open (void) pointer can hold a pointer of any type. Api says this is how i should create thread: So if I want to pass an int what I think I should do is: The second example assumes that a pointer is wide enough to store an int. In such condition type conversion (type promotion) takes place to avoid loss of data. 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. I am compiling this program in linux gcc compiler.. But you seem to suggest by your answer that the user can pass 5 to pthread_create and then perform the above cast to get it back. sound/soc/codecs/tlv320aic32x4.c:1202:18: warning: cast to smaller @Martin York: No, it doesn't depend on endiannness. Bulk update symbol size units from mm to map units in rule-based symbology. ), For those who are interested. 10) A prvalue of type pointer to void (possibly cv-qualified) can be converted to pointer to any object type. Find centralized, trusted content and collaborate around the technologies you use most. This is an old C callback mechanism so you can't change that. Thanks for pointing that out. @Shahbaz you could but I will not suggest to a C newbie to use globals. C99 defines the types "intptr_t" and "uintptr_t" which do . 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. In the case of Widening Type Casting, the lower data type (having smaller size) is converted into the higher data type (having larger size). If your standard library (even if it is not C99) happens to provide these types - use them. -1, Uggh. . (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. 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. Such pointers can be stored in 32-bit data types (for instance, int, DWORD). XCode 5.1 is change all architecture to 64 bit. For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. What is the difference between const int*, const int * const, and int const *? 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. Therefore it is perfectly valid for the compiler to throw an error for a line like. Cast Operations - Oracle what happens when we typecast normal variable to void* or any pointer variable? Wrong. I am an entry level C programmer. 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. What does casting to void* does when passing arguments to variadic functions? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. The problem just occur with Xcode 5.1. Converting one datatype into another is known as type casting or, type-conversion. What you do here is undefined behavior, and undefined behavior of very practical sort. This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. Already on GitHub? 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. reinterpret_cast is a type of casting operator used in C++. Pd = Pa; Similarly, Pc may be type cast to type int and assigned the value Pa. 1. Note:You might receive a runtime exception if the pointer contains a value unsuitable for the context. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arrays - I get the error: "cast to smaller integer type 'int' from 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? (void *)i Error: cast to 'void *' from smaller integer type 'int'. to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj 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 [.]) Mutually exclusive execution using std::atomic? 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)). A cast converts an object or value from one type to another. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. 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. C/C++ , Cerror: cast to 'void *' from smaller integer type 'int'. x is a local variable and its lifetime ends as soon as control leaves the scope it was defined in. What is the point of Thrower's Bandolier? Does a summoned creature play immediately after being summoned by a ready action?
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