The text was updated successfully, but these errors were encountered: I think the solution 3> should be the correct one. */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; unsigned long call_fn = (unsigned long)FUNC; If you preorder a special airline meal (e.g. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. But I don't want to edit code in "EAGLView.mm" because it's a "library file". Note the difference between the type casting of a variable and type casting of a pointer. 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;. Implicit Type Conversion is also known as 'automatic type 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. 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. Find centralized, trusted content and collaborate around the technologies you use most. Mutually exclusive execution using std::atomic? I have a two functions, one that returns an int, and one that takes a const void* as an argument. x is a local variable and its lifetime ends as soon as control leaves the scope it was defined in. casting from int to void* and back to int. Create an account to follow your favorite communities and start taking part in conversations. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? The difference between a and &a is the type. A cast converts an object or value from one type to another. Functions return bigint only if the parameter expression is a bigint data type. 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. 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. . Where does this (supposedly) Gibson quote come from? Don't do that. Returns a value of type new-type. Basically its a better version of (void *)i. Converts between types using a combination of implicit and user-defined conversions. Where does this (supposedly) Gibson quote come from? How to get the error message from the error code returned by GetLastError()? Therefore it is perfectly valid for the compiler to throw an error for a line like. Bulk update symbol size units from mm to map units in rule-based symbology. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. @Xax: Here's a fixed version, without the race condition: gist.github.com/depp/241d6f839b799042c409, gist.github.com/depp/3f04508a88a114734195, How Intuit democratizes AI development across teams through reusability. Thanks for pointing that out. Using indicator constraint with two variables. To learn more, see our tips on writing great answers. 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 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. 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. ncdu: What's going on with this second size column? warning C4311: 'type cast': pointer truncation from 'void *' to 'long' in ECPG test files. a cast of which the programmer should be aware of what (s)he is doing. If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. @DavidHeffernan I rephrased that sentence a little. Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. "-I.." "-Iinclude\openflow" "-I..\include\openflow" "-Iinclude\openvswitch" "-I..\include\openvsw Whats the grammar of "For those whose stories they are"? void* -> integer -> void* rather than integer -> void* -> integer. How to convert a factor to integer\numeric without loss of information? If your code has the chance to ever be ported to some platform where this doesn't hold, this won't work. 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. This is what the second warning is telling you. ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' If you preorder a special airline meal (e.g. Even though what you say regarding the lifetime of the object is true, integral types are too limited for a generic API. This is not a conversion at all. 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. */ >> -bool >> +enum conversion_safety >> unsafe_conversion_p (tree type, tree expr, bool . If you need to keep the returned address, just keep it as void*. Note:You might receive a runtime exception if the pointer contains a value unsuitable for the context. What is the purpose of non-series Shimano components? So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. 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. 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 ) Connect and share knowledge within a single location that is structured and easy to search. 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. If you really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. *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 . Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. Bulk update symbol size units from mm to map units in rule-based symbology. An open (void) pointer can hold a pointer of any type. Find centralized, trusted content and collaborate around the technologies you use most. The problem just occur with Xcode 5.1. 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". 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 Therefore, you need to change it to long long instead of long in windows for 64 bits. Mutually exclusive execution using std::atomic? Just edited. even though the compiler doesn't know you only ever pass myFcn to pthread_create in conjunction with an integer. No sense in writing a few dozen lines of extra code just to get a bunch of numbered threads. rev2023.3.3.43278. Is it possible to create a concave light? Find centralized, trusted content and collaborate around the technologies you use most. A nit: in your version, the cast to void * is unnecessary. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. How can this new ban on drag possibly be considered constitutional? There is no "correct" way to store a 64-bit pointer in an 32-bit integer. 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). Most answers just try to extract 32 useless bits out of the argument. The subreddit for the C programming language, Press J to jump to the feed. Why does flowing off the end of a non-void function without returning a value not produce a compiler error? Actions. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. On most platforms pointers and longs are the same size, but ints and pointers often are not the same size on 64bit platforms. Can I tell police to wait and call a lawyer when served with a search warrant? Thanks for contributing an answer to Stack Overflow! 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. However, you are also casting the result of this operation to (void*). Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? rev2023.3.3.43278. eg. The reinterpret_cast makes the int the size of a pointer and the warning will stop. And when assigning to a void pointer, all type information is lost. However, I believe that even if the define was for the "65536", it would not be what @kaetzacoatl wanted. ), For those who are interested. So make sure you understand what you are doing! Usually that means the pointer is allocated with. Typically, long or unsigned long is . Narrowing Casting (manually) - converting a larger type to a . 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. 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]. 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; 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. 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. This page was last modified on 12 February 2023, at 18:25. Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. From that point on, you are dealing with 32 bits. And then assign it to the double variable. For example, the main thread could wait for all of the other threads to end before terminating. Java Type Casting. [that could be a TODO - not to delay solving the ICE]. On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. But, sure, in that specific case you can pass a local variable address, type casting integer to void* [duplicate]. Asking for help, clarification, or responding to other answers. @jackdoe: It's a waste of human life to write code that "you may need in the future". Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Setting a buffer of char* with intermediate casting to int*. what does it mean to convert int to void* or vice versa? Why is there a voltage on my HDMI and coaxial cables? Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. You are getting warnings due to casting a void* to a type of a different size. linux c-pthreads: problem with local variables. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Is pthread_join a must when using pthread in linux? I understood, but that would introduce dynamic memory and ugly lifetime issues (an object allocated by one thread must be freed by some other) - all just to pass an. It is easier to understand and write than any other assembly language. Hence there is no loss in data. If the sizes are different then endianess comes into play.
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