cast to void *' from smaller integer type 'int

I agree passing a dynamically allocated pointer is fine (and I think the best way). The most general answer is - in no way. While working with Threads in C, I'm facing the warning, "warning: cast to pointer from integer of different size". 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. 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 the destination type is bool, this is a boolean conversion (see below). How to Cast a void* ponter to a char without a warning? So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. a cast of which the programmer should be aware of what (s)he is doing. Changing the type of ids would be the cleanest solution, but I decided against it when being confronted with this issue myself, as it only introduced a lot of issues with other code that is relying on ids being an int-array. Here, the Java first converts the int type data into the double type. LLNL's tutorial is bad and they should feel bad. So you know you can cast it back like this. x is a local variable and its lifetime ends as soon as control leaves the scope it was defined in. this question. 471,961 Members | 900 Online. Noncompliant Code Example (memset())For historical reasons, certain C Standard functions accept an argument of type int and convert it to either unsigned char or plain char. 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: I am using size_t here, because it is always having the same size as a pointer, no matter the platform. What I am trying to emphasis that conversion from int to pointer and back again can be frough with problems as you move from platform to platform. Difficulties with estimation of epsilon-delta limit proof. (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. 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. In the case of Widening Type Casting, the lower data type (having smaller size) is converted into the higher data type (having larger size). 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 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Well occasionally send you account related emails. -1, Uggh. ncdu: What's going on with this second size column? It is done by the compiler on its own, without any external trigger from the user. error: cast from pointer to smaller type 'unsigned int' loses information. And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. 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. Asking for help, clarification, or responding to other answers. (int) pthread_self() 64int48intuintptr_t (unsigned int) To learn more, see our tips on writing great answers. 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; */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; The only alternative is really to take time and fix all 64-bit code issues, of which there may be some non-trivial issues. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? Anw, the project still build and run normally when i use Xcode 5.0 with iOS 7.0. There is absolutely not gurantee that sizeof(int) <= sizeof(void*). This solution is in accordance with INT18-C. The calculated expression consists of two operations. Floating-point conversions 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. equal to the original pointer: First you are using a define, which is not a variable. 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. 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. Connect and share knowledge within a single location that is structured and easy to search. Casting arguments inside the function is a lot safer. Asking for help, clarification, or responding to other answers. So,solution #3 works just fine. Is it possible to create a concave light? The difference between a and &a is the type. To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. 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. error: cast from 'void*' to 'int' loses precision - Stack Overflow Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @Dinesh: could you please 1) show us those. The main point is: a pointer has a platform dependent size. Does a summoned creature play immediately after being summoned by a ready action? Casting a pointer to void* and back is valid use of reinterpret_cast<>. We have to pass address of the variable to the function because in function definition argument is pointer variable. actually no, as int my be a smaller type than a pointer ;-) But, of course with int64_t it works fine. Cast unsigned char (uint8 *) pointer to unsigned long (uint32 *) pointer The following behavior-changing defect reports were applied retroactively to previously published C++ standards. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. How do I force make/GCC to show me the commands? SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); If we want to get the exact value of 7/5 then we need explicit casting from int to float: Example: int x=7, y=5; How to correctly cast a pointer to int in a 64-bit application? How to correctly cast a pointer to int in a 64-bit application? The problem is not with casting, but with the target type loosing half of the pointer. A nit: in your version, the cast to void * is unnecessary. "clang" "-Ilib\libopenvswitch.a.p" "-Ilib" "-I..\lib" "-I." - the incident has nothing to do with me; can I use this this way? In this case, casting the pointer back to an integer is meaningless, because . Note the difference between the type casting of a variable and type casting of a pointer. Using an integer address (like &x) is probably wrong, indeed each modification you will execute on x will affect the pass behaviour. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Please help me compile Chez Scheme. void* -> integer -> void* rather than integer -> void* -> integer. 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. Sign in Remembering to delete the pointer after use so that we don't leak. 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. Identify those arcade games from a 1983 Brazilian music video, Relation between transaction data and transaction id, The difference between the phonemes /p/ and /b/ in Japanese. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. In Java, there are two types of casting: Widening Casting (automatically) - converting a smaller type to a larger type size. But, sure, in that specific case you can pass a local variable address, type casting integer to void* [duplicate]. Is pthread_join a must when using pthread in linux? Does melting sea ices rises global sea level? Press question mark to learn the rest of the keyboard shortcuts. I am compiling this program in linux gcc compiler.. Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? Do new devs get fired if they can't solve a certain bug? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Now, what happens when I run it with the thread sanitizer? INT31-C. Ensure that integer conversions do not result in lost or static_cast on the other hand should deny your stripping away the const qualifier. What is the point of Thrower's Bandolier? Casting type int to const void* - C / C++ 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. That's not a good idea if the original object (that was cast to void*) was an integer. Well it does this because you are converting a 64 bits pointer to an 32 bits integer so you loose information. If the source type is bool, the value false is converted to zero and the value true is converted to the value one of the destination type (note that if the destination type is int, this is an integer promotion, not an integer conversion). Yeah, the tutorial is doing it wrong. As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). In C (int)b is called an explicit conversion, i.e. what happens when we typecast normal variable to void* or any pointer variable? 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). 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;. 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. Not the answer you're looking for? Not the answer you're looking for? c - How to cast an integer to void pointer? - Stack Overflow Visit Microsoft Q&A to post new questions. reinterpret_cast<void *>(42)). I would create a structure and pass that as void* to pthread_create. ), Styling contours by colour and by line thickness in QGIS. Can we typecast void into int? - Quora [PATCH] platform/x86: hp-wmi: Fix cast to smaller integer type warning You can convert the values from one type to another explicitly using the cast operator as follows (type_name) expression eg. Find centralized, trusted content and collaborate around the technologies you use most. How to use Slater Type Orbitals as a basis functions in matrix method correctly? I think the solution 3> should be the correct one. Can I tell police to wait and call a lawyer when served with a search warrant? */ >> -bool >> +enum conversion_safety >> unsafe_conversion_p (tree type, tree expr, bool . (void *)i Error: cast to 'void *' from smaller integer type 'int'. arrays - I get the error: "cast to smaller integer type 'int' from 1. To be honest, I think, clang is too restrictive here. I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. 4. Type Conversions - C in a Nutshell [Book] - O'Reilly Online Learning 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 program can be set in such a way to ask the user to inform the type of data and . Why does setupterm terminate the program? This is a fine way to pass integers to new pthreads, if that is what you need. Converting a void* to an int is non-portable way that may work or may not! Yeah, the tutorial is doing it wrong. On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. Why is this sentence from The Great Gatsby grammatical? I have a two functions, one that returns an int, and one that takes a const void* as an argument. Why does Mister Mxyzptlk need to have a weakness in the comics? *PATCH] platform/x86: hp-wmi: Fix cast to smaller integer type warning @ 2023-01-23 13:28 Hans de Goede 2023-01-23 13:56 ` Hans de Goede 0 siblings, 1 reply; 2+ messages in thread From: Hans de Goede @ 2023-01-23 13:28 UTC (permalink / raw) To: Mark Gross Cc: Hans de Goede, Andy Shevchenko, platform-driver-x86, kernel test robot Fix the following . returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); casting from int to void* and back to int. Again, all of the answers above missed the point badly. 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). This allows you to reinterpret the void * as an int. There's no proper way to cast this to int in general case. Only the following conversions can be done with static_cast, except when such conversions would cast away constness or volatility. A missing cast in the new fast > enumeration code. If you need to keep the returned address, just keep it as void*. If the function had the correct signature you would not need to cast it explicitly. Type casting is when you assign a value of one primitive data type to another type. 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 pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. windows meson: cast to 'HANDLE' (aka 'void *') from smaller integer STR34-C. Cast characters to unsigned char before converting to larger Before I update Xcode, my project still can build and run normally with all devices. But then you need to cast your arguments inside your thread function which is quite unsafe cf. 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. reinterpret_cast conversion - cppreference.com ncdu: What's going on with this second size column? The preprocesor absolutely will not perform arithmetic. 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. Clang warnings for an invalid casting? - The FreeBSD Forums I have a function with prototype void* myFcn(void* arg) which is used as the starting point for a pthread. For integer casts in specific, using into() signals that . How to use Slater Type Orbitals as a basis functions in matrix method correctly? But gcc always give me a warning, that i cannot cast an int to a void*. this way you won't get any warning. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? How can this new ban on drag possibly be considered constitutional? This will get you a pointer from a 32 bit offset: A function pointer is incompatible to void* (and any other non function pointer). What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? Don't do that. Asking for help, clarification, or responding to other answers. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Mutually exclusive execution using std::atomic? A cast is a way of explicitly informing the compiler that you intend to make the conversion and that you are aware that data loss might occur, or the cast may fail at run time. (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. Returns a value of type new-type. Using indicator constraint with two variables. 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 [.]) Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS. How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. 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. And, most of these will not even work on gcc4. ", "? A void pointer can be really useful if the programmer is not sure about the data type of data inputted by the end user. then converted back to pointer to void, and the result will compare In such a case the programmer can use a void pointer to point to the location of the unknown data type. 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. Why is there a voltage on my HDMI and coaxial cables? Connect and share knowledge within a single location that is structured and easy to search.

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