What is "cast from integer to pointer of different size" warning? There is no "correct" way to store a 64-bit pointer in an 32-bit integer. Again, all of the answers above missed the point badly. Disconnect between goals and daily tasksIs it me, or the industry? For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. Projects. } SCAN_END_SINGLE(ATTR) @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. On most platforms pointers and longs are the same size, but ints and pointers often are not the same size on 64bit platforms. Implicit Type Conversion in C with Examples - GeeksforGeeks The text was updated successfully, but these errors were encountered: 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. Narrowing Casting (manually) - converting a larger type to a . By clicking Sign up for GitHub, you agree to our terms of service and I'm unfamiliar with XCode, but the solution should be something like follows: Most of the "solutions" above can lose part of the pointer address when casting to a smaller type. Update: Today, i download the latest version of cocos2d-x (cocos2d-x 2.2.3). Why does flowing off the end of a non-void function without returning a value not produce a compiler error? 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. This is flat out wrong. rev2023.3.3.43278. Half your pointer will be garbage. Well occasionally send you account related emails. 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. Using an integer address (like &x) is probably wrong, indeed each modification you will execute on x will affect the pass behaviour. Connect and share knowledge within a single location that is structured and easy to search. The result is the same as implicit conversion from the enum's underlying type to the destination type. Use of Void pointers in C programming language ^~~~~~~~~~~~~~~~~~~~~ Is a PhD visitor considered as a visiting scholar. Whats the grammar of "For those whose stories they are"? The main point is: a pointer has a platform dependent size. windows meson: cast to smaller integer type 'unsigned long' from 'void ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' As Ferruccio said, int must be replaced with intptr_t to make the program meaningful. Apparently the clang version in Xcode 5.1 and above is more strict about potential 32bit vs. 64 bit incompatibilities in source code than older clang versions have been. When is casting void pointer needed in C? to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj But I don't want to edit code in "EAGLView.mm" because it's a "library file". A cast converts an object or value from one type to another. @Shahbaz you could but I will not suggest to a C newbie to use globals. Anw, the project still build and run normally when i use Xcode 5.0 with iOS 7.0. Casting and type conversions - C# Programming Guide This solution is in accordance with INT18-C. */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; 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. ncdu: What's going on with this second size column? ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] Linear regulator thermal information missing in datasheet. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Why is this sentence from The Great Gatsby grammatical? you can just change architecture to support 32 bit compilation by all below in in Build Settings. Types - D Programming Language Since the 'size' argument for your function is the number of bytes each element in the array needs, I think casting the pointerto (char*) is appropriate. Error while setting app icon and launch image in xcode 5.1. If you need to keep the returned address, just keep it as void*. To learn more, see our tips on writing great answers. You should perform type conversion based on 64bit build system because the type "int" supports only -32768 ~ 32768. But this code pass the normal variable .. equal to the original pointer: First you are using a define, which is not a variable. A void pointer can be really useful if the programmer is not sure about the data type of data inputted by the end user. 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 The int data type is the primary integer data type in SQL Server. Not the answer you're looking for? You need to cast the void* pointer to a char* pointer - and then dereference that char* pointer to give you the char that it points to! This will get you a pointer from a 32 bit offset: A function pointer is incompatible to void* (and any other non function pointer). Returns a value of type new-type. @DavidHeffernan, sane thread APIs wouldn't send integral data to the thread procedures, they would send pointers. The preprocesor absolutely will not perform arithmetic. Is it possible to create a concave light? The problem just occur with Xcode 5.1. Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. But then you need to cast your arguments inside your thread function which is quite unsafe cf. 7.1 New Cast Operations The C++ standard defines new cast operations that provide finer control than previous cast operations. To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. How to correctly cast a pointer to int in a 64-bit application? While working with Threads in C, I'm facing the warning, "warning: cast to pointer from integer of different size". Java Type Casting - W3Schools Typically, long or unsigned long is . This allows you to reinterpret the void * as an int. Making statements based on opinion; back them up with references or personal experience. Next, when doing pointer arithmetic, the addition operation will use the pointer's type to determine how many bytes to add to it when incrementing it. How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. 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). Why do small African island nations perform better than African continental nations, considering democracy and human development? [] 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). INT31-C. Ensure that integer conversions do not result in lost or It's always a good practice to put your #define's in brackets to avoid such surprise. Taking the above declarations of A, D, ch of the . The problem is not with casting, but with the target type loosing half of the pointer. Thank you all for your feedback. Remarks. Most answers just try to extract 32 useless bits out of the argument. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? ^~~~~~~~~~~~~~~~~~~ : iPhone Retina 4-inch 64-bit) is selected. This is not even remotely "the correct answer". If your standard library (even if it is not C99) happens to provide these types - use them. Actions. Cast unsigned char (uint8 *) pointer to unsigned long (uint32 *) pointer Converting one datatype into another is known as type casting or, type-conversion. c - type casting integer to void* - Stack Overflow Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. What does casting to void* does when passing arguments to variadic functions? So you could do this: Note: As sbi points out this would require a change on the OP call to create the thread. Safe downcast may be done with dynamic_cast. This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. . Visit Microsoft Q&A to post new questions. The dynamic_cast<>operator provides a way to check the actual type of a pointer to a polymorphic class. Have a question about this project? SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); The difference between the phonemes /p/ and /b/ in Japanese. 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;. Converts between types using a combination of implicit and user-defined conversions. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, error: cast from void* to int loses precision, cast to pointer from integer of different size, pthread code. The OP wanted to convert a pointer value to a int value, instead, most the answers, one way or the other, tried to wrongly convert the content of arg points to to a int value. It is commonly called a pointer to T and its type is T*. ), Styling contours by colour and by line thickness in QGIS. How create a simple program using threads in C? Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). How can this new ban on drag possibly be considered constitutional? The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. 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. You may declare a const int variable and cast its reference to the void*. error: cast from 'void*' to 'int' loses precision - Stack Overflow Keep in mind that thrArg should exist till the myFcn() uses it. Find centralized, trusted content and collaborate around the technologies you use most. [PATCH] platform/x86: hp-wmi: Fix cast to smaller integer type warning An object pointer (including void*) or function pointer can be converted to an integer type using reinterpret_cast. privacy statement. 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 (i.e. Is pthread_join a must when using pthread in linux? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. What happens if you typecast as unsigned first? returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); You need to pass an actual pointer. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. (int) pthread_self() 64int48intuintptr_t (unsigned int) this question. ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' This is a fine way to pass integers to new pthreads, if that is what you need. [that could be a TODO - not to delay solving the ICE]. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? It modifies >> Wconversion-real.c, Wconversion-real-integer.c and pr35635.c to be more >> specific > > If the patch passes existing tests, I'd be inclined to leave them > tests alone and add new ones that are specific to what this patch > changes. Making statements based on opinion; back them up with references or personal experience. It is easier to understand and write than any other assembly language. Usually that means the pointer is allocated with. Please help me compile Chez Scheme. a cast of which the programmer should be aware of what (s)he is doing. Casting Pointers - IBM Put your define inside a bracket: #define M_TABLE_SIZE (64*1024) Now, you can do: static const void* M_OFFSET = (void*) M_TABLE_SIZE; without a problem. I have a two functions, one that returns an int, and one that takes a const void* as an argument. Connect and share knowledge within a single location that is structured and easy to search. Functions return bigint only if the parameter expression is a bigint data type. B programing language is a language based on basic combined programming or a BCPL, and it is the precursor of the C programming language. C++ how to get the address stored in a void pointer? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. "-I.." "-Iinclude\openflow" "-I..\include\openflow" "-Iinclude\openvswitch" "-I..\include\openvsw The most general answer is - in no way. Based on the design of this function, which modification is right. All character types are to be converted to an integer. For integer casts in specific, using into() signals that . GitHub. Recovering from a blunder I made while emailing a professor. Implementation-dependent. I think the solution 3> should be the correct one. 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. And when assigning to a void pointer, all type information is lost. I don't see how anything bad can happen . Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. And in this context, it is very very very common to see programmers lazily type cast the. "because the type "int" supports only -32768 ~ 32768" This is not true for any modern desktop or mobile OS or any OS that is targeted by cocos2d-x. I have a function with prototype void* myFcn(void* arg) which is used as the starting point for a pthread. What does it mean to convert int to void* or vice versa? 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. windows meson: cast to 'HANDLE' (aka 'void *') from smaller integer error: cast from pointer to smaller type 'unsigned int' loses What is the purpose of non-series Shimano components? To cast such pointers to 32-bit types and vice versa special functions are used: void * Handle64ToHandle ( const void * POINTER_64 h ) void * POINTER_64 HandleToHandle64 ( const void *h ) long HandleToLong ( const void *h ) unsigned long HandleToUlong ( const void *h ) Sign in This is why you got Error 1 C2036, from your post. 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. Are there tables of wastage rates for different fruit and veg? Mutually exclusive execution using std::atomic? STR34-C. Cast characters to unsigned char before converting to larger I need to cast the int from the first function so that I can use it as an argument for the second function. 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. Put your define inside a bracket: without a problem. vegan) just to try it, does this inconvenience the caterers and staff? How Intuit democratizes AI development across teams through reusability. However, I believe that even if the define was for the "65536", it would not be what @kaetzacoatl wanted. 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. If you do this, you have the thread reference a value that (hopefully still) lives in some other thread. Offline ImPer Westermark over 11 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. static_cast conversion - cppreference.com Using Kolmogorov complexity to measure difficulty of problems? converted back to pointer to void, and the result will compare equal Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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 the object expression refers or points to is actually a base class subobject of an object of type D, the result refers to the enclosing object of type D. Otherwise, the behavior is undefined: When the target type is bool (possibly cv-qualified), the result is false if the original value is zero and true for all other values. this way I convert an int to a void* which is much better than converting a void* to an int. On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . And in the function you get the value of the pointer by using the dereference operator *: Please read why glib provide macros for this kind of conversions, there's no need to repeat the text here. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. Create an account to follow your favorite communities and start taking part in conversations. You can only do this if you use a synchronization primitive to ensure that there is no race condition. Asking for help, clarification, or responding to other answers. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, "what happen when typcating normal variable to void* or any pointer variable?" 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 [.]) Casting type int to const void* - C / C++ 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. From the question I presume the OP does. It generally takes place when in an expression more than one data type is present. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @Dinesh: could you please 1) show us those. I have looked around and can't seem to find any information on how to do this. If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. What is the purpose of this D-shaped ring at the base of the tongue on my hiking boots? ", "? Before I update Xcode, my project still can build and run normally with all devices. . Such pointers can be stored in 32-bit data types (for instance, int, DWORD). Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? Floating-point conversions 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. The point is (probably) that the value passed to the thread is an integer value, not really a 'void *'. If the original pointer value represents an address of a byte in memory that does not satisfy the alignment requirement of the target type, then the resulting pointer value is unspecified. Otherwise, if the original pointer value points to an object a, and there is an object b of the . Use #include to define it. Remembering to delete the pointer after use so that we don't leak. How to use Slater Type Orbitals as a basis functions in matrix method correctly? iphone - Error "Cast from pointer to smaller type 'int' loses 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). Find centralized, trusted content and collaborate around the technologies you use most. Cast a smaller integer to a larger integer - community - The Rust You are getting warnings due to casting a void* to a type of a different size. } SCAN_END_SINGLE(ATTR) 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.. Can we typecast void into int? - Quora In this case, casting the pointer back to an integer is meaningless, because . Thanks Jonathan, I was thinking about my answer in another thread: AraK is correct, passing integers a pointers are not necessarily interchangeable. I have the following function and when I compile it under VS.NET 2005, the following compile warnings show up: Warning1warning C4311: 'type cast' : pointer truncation from 'void *' to 'long'c:\temp\testone\lib\utils.c56Warning2warning C4312: 'type cast' : conversion from 'unsigned long' to 'void *' of greater sizec:\temp\testone\lib\utils.c56, Code Snippet This forum has migrated to Microsoft Q&A. Star 675. I am compiling this program in linux gcc compiler.. ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' Can Martian regolith be easily melted with microwaves? I would create a structure and pass that as void* to pthread_create. That could create all kinds of trouble. Thanks. Here, the Java first converts the int type data into the double type. long guarantees a pointer size on Linux on any machine. ", "!"? How to correctly cast a pointer to int in a 64-bit application? A nit: in your version, the cast to void * is unnecessary. Note:You might receive a runtime exception if the pointer contains a value unsuitable for the context. FAILED: lib/libopenvswitch.a.p/odp-util.c.obj Find centralized, trusted content and collaborate around the technologies you use most. The result is implementation-defined and typically yields the numeric address of the byte in memory that the pointer pointers to. Number Type Cast | Qt Forum How do I work around the GCC "error: cast from SourceLocation* to int loses precision" error when compiling cmockery.c? Asking for help, clarification, or responding to other answers. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. Where does this (supposedly) Gibson quote come from? Fork 63. From that point on, you are dealing with 32 bits. Mutually exclusive execution using std::atomic? Implicit conversions - cppreference.com Compile error on Android ARM Issue #163 cisco/ChezScheme */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 returnPtr[j] = (void *) (ptr + i); // <<< Compile Errors, Error1error C2036: 'void *' : unknown sizec:\temp\testone\lib\utils.c57, 2> returnPtr[j] = (void *) ((long*)ptr + i); // <<< No compile errors, 3> returnPtr[j] = (void *) ((char*)ptr + i); // <<< No compile errors.
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