equal to the original pointer: First you are using a define, which is not a variable. then converted back to pointer to void, and the result will compare I am an entry level C programmer. 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. sound/soc/codecs/tlv320aic32x4.c:1202:18: warning: cast to smaller C++ how to get the address stored in a void pointer? Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul Netdev Archive on lore.kernel.org help / color / mirror / Atom feed * [mst-vhost:vhost 5/52] drivers/block/virtio_blk.c:539:21: warning: assignment to 'void *' from . Is it possible to create a concave light? error: cast from pointer to smaller type 'unsigned int' loses information. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? Connect and share knowledge within a single location that is structured and easy to search. Click to see the query in the CodeQL repository. How to use Slater Type Orbitals as a basis functions in matrix method correctly? Bulk update symbol size units from mm to map units in rule-based symbology. In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. Why does Mister Mxyzptlk need to have a weakness in the comics? But, sure, in that specific case you can pass a local variable address, type casting integer to void* [duplicate]. What is the point of Thrower's Bandolier? even though the compiler doesn't know you only ever pass myFcn to pthread_create in conjunction with an integer. Connect and share knowledge within a single location that is structured and easy to search. 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. The problem was there before, you just are being notified of it. It is easier to understand and write than any other assembly language. Asking for help, clarification, or responding to other answers. If the destination type is bool, this is a boolean conversion (see below). Making statements based on opinion; back them up with references or personal experience. But then you need to cast your arguments inside your thread function which is quite unsafe cf. If the value is ever used as pointer again that will prove to be an extremely bad idea. 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. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. How to use Slater Type Orbitals as a basis functions in matrix method correctly? Connect and share knowledge within a single location that is structured and easy to search. 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. windows meson: cast to smaller integer type 'unsigned long' from 'void Well occasionally send you account related emails. Is it possible to create a concave light? If you really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. this way I convert an int to a void* which is much better than converting a void* to an int. "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. : iPhone Retina 4-inch 64-bit) is selected. ncdu: What's going on with this second size column? For integer casts in specific, using into() signals that . An object pointer (including void*) or function pointer can be converted to an integer type using reinterpret_cast. Using Kolmogorov complexity to measure difficulty of problems? error: cast from 'void*' to 'int' loses precision - Stack Overflow */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. In the case of Widening Type Casting, the lower data type (having smaller size) is converted into the higher data type (having larger size). rev2023.3.3.43278. Yeah, the tutorial is doing it wrong. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. We have to pass address of the variable to the function because in function definition argument is pointer variable. Offline ImPer Westermark over 11 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. Mutually exclusive execution using std::atomic? SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); Thanks Jonathan, I was thinking about my answer in another thread: AraK is correct, passing integers a pointers are not necessarily interchangeable. I have a two functions, one that returns an int, and one that takes a const void* as an argument. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? error: comparison between pointer and integer ('int' and 'string' (aka 'char *')), CS50 Caesar program is working but check50 says it isn't. Even though what you say regarding the lifetime of the object is true, integral types are too limited for a generic API. @DavidHeffernan I rephrased that sentence a little. By clicking Sign up for GitHub, you agree to our terms of service and The main point is: a pointer has a platform dependent size. What is the difference between const int*, const int * const, and int const *? The correct answer is, if one does not mind losing data precision. 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. unsigned long call_fn = (unsigned long)FUNC; Thanks for contributing an answer to Stack Overflow! Once you manage to make this cast, then what?! 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. "-I.." "-Iinclude\openflow" "-I..\include\openflow" "-Iinclude\openvswitch" "-I..\include\openvsw How to get the error message from the error code returned by GetLastError()? Making statements based on opinion; back them up with references or personal experience. 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. If you preorder a special airline meal (e.g. ^~~~~~~~~~~~~~~~~~~~ You are getting warnings due to casting a void* to a type of a different size. Based on the design of this function, which modification is right. Using indicator constraint with two variables. 10) A prvalue of type pointer to void (possibly cv-qualified) can be converted to pointer to any object type. Get the address of a callback function to call dynamically in C++, error: call of overloaded function ambiguous, error: cast from to unsigned int loses precision [-fpermissive]. On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. Connect and share knowledge within a single location that is structured and easy to search. The difference between the phonemes /p/ and /b/ in Japanese. So you could do this: Note: As sbi points out this would require a change on the OP call to create the thread. returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); If you cast an int pointer int, you might get back a different integer. If you need to keep the returned address, just keep it as void*. 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. 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. Half your pointer will be garbage. 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. You can only do this if you use a synchronization primitive to ensure that there is no race condition. Casting type int to const void* - C / C++ Keep in mind that thrArg should exist till the myFcn() uses it. Use returnPtr[j] = (void *) ((long)ptr + i); ). Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. what does it mean to convert int to void* or vice versa? Please tell me error: cast from 'void*' to 'int' loses precision, How Intuit democratizes AI development across teams through reusability. GitHub Skip to content Product Solutions Open Source Pricing Sign in Sign up smadaminov / ovs-dpdk-meson-issues Public Notifications Fork 1 Star 1 Code Issues 66 Pull requests Actions Projects 1 Security Insights New issue Bulk update symbol size units from mm to map units in rule-based symbology. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' I have a function with prototype void* myFcn(void* arg) which is used as the starting point for a pthread. You use the address-of operator & to do that. Can Martian regolith be easily melted with microwaves? Implicit conversions - cppreference.com this way you won't get any warning. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Sign in 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 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". Just re-enforcing the old behavior of Xcode 5.0 and earlier versions, that already cut away parts of the address by casting it to int, won't introduce any new bugs and avoids the need to learn and understand lots of implementation-internal cocos code. Find centralized, trusted content and collaborate around the technologies you use most. Note the difference between the type casting of a variable and type casting of a pointer. What is "cast from integer to pointer of different size" warning? FAILED: lib/libopenvswitch.a.p/odp-util.c.obj itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" Acidity of alcohols and basicity of amines. Not the answer you're looking for? To learn more, see our tips on writing great answers. Type Casting Of Pointers in C - Computer Notes As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. 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. What does casting to void* does when passing arguments to variadic functions? 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. Narrowing Casting (manually) - converting a larger type to a . @Shahbaz you could but I will not suggest to a C newbie to use globals. Find centralized, trusted content and collaborate around the technologies you use most. Projects. What you do here is undefined behavior, and undefined behavior of very practical sort. So make sure you understand what you are doing! 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.
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