If you convert (void*) to (long) no precision is lost, then by assigning the (long) to an (int), it properly truncates the number to fit. I have a function with prototype void* myFcn(void* arg) which is used as the starting point for a pthread. I think the solution 3> should be the correct one. 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 . SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); 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. Click to see the query in the CodeQL repository. @BlueMoon Thanks a lot! Therefore it is perfectly valid for the compiler to throw an error for a line like. Thanks Jonathan, I was thinking about my answer in another thread: AraK is correct, passing integers a pointers are not necessarily interchangeable. I recall there was a TreeNode(int) early on prior to 1.0 release I can't remember why I removed it, if I should felt it was easy enough to cast to (void*) or if it was because it created type inference conflict at the call site. Functions return bigint only if the parameter expression is a bigint data type. 10) A prvalue of type pointer to void (possibly cv-qualified) can be converted to pointer to any object type. This returns the first 32 bits of the pointer which may be the top or the bottom depending on big versus little endian, as comment #2 said. The program can be set in such a way to ask the user to inform the type of data and . The calculated expression consists of two operations. And then assign it to the double variable. @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. 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. LLNL's tutorial is bad and they should feel bad. The text was updated successfully, but these errors were encountered: Find centralized, trusted content and collaborate around the technologies you use most. Well occasionally send you account related emails. . How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. You are correct, but cocos actually only uses that address as a unique id. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. There is no "correct" way to store a 64-bit pointer in an 32-bit integer. Keep in mind that thrArg should exist till the myFcn() uses it. Replacing broken pins/legs on a DIP IC package, How to handle a hobby that makes income in US. Why did Ukraine abstain from the UNHRC vote on China? You need to pass an actual pointer. There is absolutely not gurantee that sizeof(int) <= sizeof(void*). Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? Based on the design of this function, which modification is right. Floating-point conversions casting from int to void* and back to int. Projects. error: comparison between pointer and integer ('int' and 'string' (aka 'char *')), CS50 Caesar program is working but check50 says it isn't. byte -> short -> char -> int -> long -> float -> double. C99 defines the types "intptr_t" and "uintptr_t" which do . use $(ARCHS_STANDARD_32_BIT) at Architecture instead of $(ARCHS_STANDARD). Does a summoned creature play immediately after being summoned by a ready action? Thanks for contributing an answer to Stack Overflow! and how to print the thread id of 2d array argument? AC Op-amp integrator with DC Gain Control in LTspice. 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. Thanks for contributing an answer to Stack Overflow! Find centralized, trusted content and collaborate around the technologies you use most. The only exception is exotic systems with the SILP64 data model, where the size of int is also 64 bits. 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! To subscribe to this RSS feed, copy and paste this URL into your RSS reader. itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" Terrible solution. In C (int)b is called an explicit conversion, i.e. @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. The difference between a and &a is the type. Instead of using a long cast, you should cast to size_t. Again, all of the answers above missed the point badly. How to correctly cast a pointer to int in a 64-bit application? I'm new to coding and am trying to implement a simple program on my own, that prompts the user the number of residents in an apt complex, the prompts the user to enter the names and apt numbers of each resident. 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. It is easier to understand and write than any other assembly language. Not the answer you're looking for? Why does Mister Mxyzptlk need to have a weakness in the comics? Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? How do I force make/GCC to show me the commands? What is the point of Thrower's Bandolier? Difficulties with estimation of epsilon-delta limit proof. In such a case the programmer can use a void pointer to point to the location of the unknown data type. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? Please tell me error: cast from 'void*' to 'int' loses precision, How Intuit democratizes AI development across teams through reusability. Pull requests. error: cast from pointer to smaller type 'unsigned int' loses information. This is an old C callback mechanism so you can't change that. Bulk update symbol size units from mm to map units in rule-based symbology. Connect and share knowledge within a single location that is structured and easy to search. 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]. Asking for help, clarification, or responding to other answers. 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. -1, Uggh. rev2023.3.3.43278. @DietrichEpp can you explain what is race condition with using. } SCAN_END_SINGLE(ATTR) The problem was there before, you just are being notified of it. */ >> -bool >> +enum conversion_safety >> unsafe_conversion_p (tree type, tree expr, bool . Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. Anw, the project still build and run normally when i use Xcode 5.0 with iOS 7.0. SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ whether it was an actual problem is a different matter though. Whats the grammar of "For those whose stories they are"? Find centralized, trusted content and collaborate around the technologies you use most. You can fix this error by replacing this line of code. 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). Once you manage to make this cast, then what?! 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. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. If you need to keep the returned address, just keep it as void*. 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. 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. 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. You can use a 64 bits integer instead howerver I usually use a function with the right prototype and I cast the function type : Visit Microsoft Q&A to post new questions. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? But assuming that it is, as long as the caller and the callee agree, you can do that sort of thing. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. Don't pass your int as a void*, pass a int* to your int, so you can cast the void* to an int* and copy the dereferenced pointer to your int. On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? Can Martian regolith be easily melted with microwaves? If you preorder a special airline meal (e.g. 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. However, I believe that even if the define was for the "65536", it would not be what @kaetzacoatl wanted. return ((void **) returnPtr);} /* Matrix() */. Linear regulator thermal information missing in datasheet. As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. What happens if you typecast as unsigned first? How do I work around the GCC "error: cast from SourceLocation* to int loses precision" error when compiling cmockery.c? Have a question about this project? Create an account to follow your favorite communities and start taking part in conversations. 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. 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. reinterpret_cast<void *>(42)). The proper way is to cast it to another pointer type. 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. An object pointer (including void*) or function pointer can be converted to an integer type using reinterpret_cast. A cast specifies a conversion from one type to another. 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. If you do this, you have the thread reference a value that (hopefully still) lives in some other thread. Why is this sentence from The Great Gatsby grammatical? Making statements based on opinion; back them up with references or personal experience. @jackdoe: It's a waste of human life to write code that "you may need in the future". This will only compile if the destination type is long enough. It is commonly called a pointer to T and its type is T*. However even though their types are different, the address is going to be the same. To learn more, see our tips on writing great answers. Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. Are there tables of wastage rates for different fruit and veg? ), Styling contours by colour and by line thickness in QGIS. In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. 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. 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
I have a two functions, one that returns an int, and one that takes a const void* as an argument. If the sizes are different then endianess comes into play. In this case, casting the pointer back to an integer is meaningless, because . How to notate a grace note at the start of a bar with lilypond? */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j;
Where does this (supposedly) Gibson quote come from? Getting Command /bin/sh failed with exit code 65 Error with Xcode 5.1 . But I don't want to edit code in "EAGLView.mm" because it's a "library file". If the original type is a void *, converting to an int may lose date on platforms where sizeof(void *) != sizeof(int) (which is true of LP64 programming model). @Martin York: No, it doesn't depend on endiannness. How to convert a factor to integer\numeric without loss of information? ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] Any help with this is appreciated. 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). 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. rev2023.3.3.43278. If that happens soon after the call to pthread_create() then you have a race condition, because there's a chance that the thread will attempt to read x's value after it's life has ended, which invokes undefined behavior. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. You use the address-of operator & to do that. There's probably little you can do except look or hope for a fixed 2.x version or upgrade to 3.x (I would assume it's 64-bit safe but this is just a guess, do research this issue before you upgrade). What is the purpose of non-series Shimano components? then converted back to pointer to void, and the result will compare : iPhone Retina 4-inch 64-bit) is selected. 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. 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. C/C++ , Cerror: cast to 'void *' from smaller integer type 'int'. Here, the Java first converts the int type data into the double type. 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. B language was designed to develop . 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. We have to pass address of the variable to the function because in function definition argument is pointer variable. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). What is the purpose of this D-shaped ring at the base of the tongue on my hiking boots? To learn more, see our tips on writing great answers. I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. The subreddit for the C programming language, Press J to jump to the feed. 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. In my case, I was using a 32-bit value that needed to be passed to an OpenGL function as a void * representing an offset into a buffer. How can this new ban on drag possibly be considered constitutional? Making statements based on opinion; back them up with references or personal experience. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Can Martian regolith be easily melted with microwaves? rev2023.3.3.43278. SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); pthread create managing values generated in function (in c), Establishing TCP socket connection between PHP client and C server on Ubuntu. If you cast an int pointer int, you might get back a different integer. And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. There's no proper way to cast this to int in general case. 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. How to tell which packages are held back due to phased updates, Identify those arcade games from a 1983 Brazilian music video. *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 . Put your define inside a bracket: without a problem. All float types are to be converted to double. } SCAN_END_SINGLE(ATTR) "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. 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. 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; 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. XCode 5.1 is change all architecture to 64 bit. The reinterpret_cast makes the int the size of a pointer and the warning will stop. Maybe you can try this too. The problem just occur with Xcode 5.1. So make sure you understand what you are doing! Then i can continue compiling. Not the answer you're looking for? should we also have a diagnostic for the (presumed) user error? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. I need to cast the int from the first function so that I can use it as an argument for the second function. 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. ^~~~~~~~~~~~~~~~~~~~ ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' Offline ImPer Westermark over 11 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. This is why you got Error 1 C2036, from your post. 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. SCAN_PUT(ATTR, NULL); Please help me compile Chez Scheme. This is flat out wrong. Thanks. (int*)Pc = pa; After the execution of the above code all the three pointers, i.e., Pa, Pd, and Pc, point to the value 150. To be honest, I think, clang is too restrictive here. Mutually exclusive execution using std::atomic? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. (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. Thank you all for your feedback. In such condition type conversion (type promotion) takes place to avoid loss of data.