Using indicator constraint with two variables. Implicit conversions - cppreference.com Keep in mind that thrArg should exist till the myFcn() uses it. For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. As for the stack, I've written a few libraries using pthreds, thus I don't agree that what you describe "is quite often the case". If your standard library (even if it is not C99) happens to provide these types - use them. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. You are right! By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Basically its a better version of (void *)i. There's no proper way to cast this to int in general case. As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). Casting a pointer to void* and back is valid use of reinterpret_cast<>. 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. Recovering from a blunder I made while emailing a professor. 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; converted back to pointer to void, and the result will compare equal Making statements based on opinion; back them up with references or personal experience. It's always a good practice to put your #define's in brackets to avoid such surprise. 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;. 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. But I don't want to edit code in "EAGLView.mm" because it's a "library file". error: cast from pointer to smaller type 'unsigned int' loses information. 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. In this case, casting the pointer back to an integer is meaningless, because . Once you manage to make this cast, then what?! rev2023.3.3.43278. Please note that the error I am receiving is "cast to smaller integer type 'int' from 'string' (aka 'char *')" referencing line of code: while (isalpha (residents [i].name) == 0). lexborisov Modest Public. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. But assuming that it is, as long as the caller and the callee agree, you can do that sort of thing. Implicit Type Conversion in C with Examples - GeeksforGeeks By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. This is what the second warning is telling you. And then assign it to the double variable. Is it possible to create a concave light? The calculated expression consists of two operations. Can we typecast void into int? - Quora reinterpret_cast conversion - cppreference.com It was derived from the BCPL, and the name of the b language is possibly from the BCPL contraction. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Not the answer you're looking for? Java Type Casting (With Examples) - Programiz linux c-pthreads: problem with local variables. However, you are also casting the result of this operation to (void*). @DavidHeffernan I rephrased that sentence a little. privacy statement. Taking the above declarations of A, D, ch of the . What does it mean to convert int to void* or vice versa? 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. No sense in writing a few dozen lines of extra code just to get a bunch of numbered threads. Replacing broken pins/legs on a DIP IC package, AC Op-amp integrator with DC Gain Control in LTspice. This solution is in accordance with INT18-C. 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. I would create a structure and pass that as void* to pthread_create. Re: [PATCH, PR 53001] Re: Patch to split out new warning flag for sound/soc/codecs/tlv320aic32x4.c:1202:18: warning: cast to smaller And in this context, it is very very very common to see programmers lazily type cast the. Wrong. Using Kolmogorov complexity to measure difficulty of problems? If your code has the chance to ever be ported to some platform where this doesn't hold, this won't work. ncdu: What's going on with this second size column? c - How to cast an integer to void pointer? - Stack Overflow Since all pointers on 64-bit Windows are 64 bits, you are growing the data size from 32 bits backto 64 bits. ^~~~~~~~~~~~~~~~~~~~~ [that could be a TODO - not to delay solving the ICE]. Issues. How Intuit democratizes AI development across teams through reusability. BUT converting a pointer to void* and back again is well supported (everywhere). This is an old C callback mechanism so you can't change that. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' C - Type Casting - tutorialspoint.com My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? How to correctly cast a pointer to int in a 64-bit application? What is the purpose of this D-shaped ring at the base of the tongue on my hiking boots? Disconnect between goals and daily tasksIs it me, or the industry? Use #include to define it. This page was last modified on 12 February 2023, at 18:25. I'm trying to learn pthreads and thing that keeps bugging me is how do i really pass argument to the function. Pd = Pa; Similarly, Pc may be type cast to type int and assigned the value Pa. 1. If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . Type casting is when you assign a value of one primitive data type to another type. Whats the grammar of "For those whose stories they are"? Thanks Jonathan, I was thinking about my answer in another thread: AraK is correct, passing integers a pointers are not necessarily interchangeable. Please tell me error: cast from 'void*' to 'int' loses precision, How Intuit democratizes AI development across teams through reusability. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. error: cast from pointer to smaller type 'unsigned int' loses Before I update Xcode, my project still can build and run normally with all devices. C++ Tutorial => Conversion between pointer and integer It is commonly called a pointer to T and its type is T*. 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 . Here, the Java first converts the int type data into the double type. Just edited. In such condition type conversion (type promotion) takes place to avoid loss of data. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' How Intuit democratizes AI development across teams through reusability. 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. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Typically, long or unsigned long is . No idea how it amassed 27 upvotes?! So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" [mst-vhost:vhost 5/52] drivers/block/virtio_blk.c:539:21: warning The difference between a and &a is the type. This allows you to reinterpret the void * as an int. Find centralized, trusted content and collaborate around the technologies you use most. 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). Star 675. 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. actually no, as int my be a smaller type than a pointer ;-) But, of course with int64_t it works fine. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, You should be doing int x = *((int *)arg); You are casting from void * to int that is why you get the warning. Actions. The proper way is to cast it to another pointer type. On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. INT36-C. Converting a pointer to integer or integer to pointer Asking for help, clarification, or responding to other answers. Linear regulator thermal information missing in datasheet. Does melting sea ices rises global sea level? 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). By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. But the problem has still happened. From that point on, you are dealing with 32 bits. I need to convert the argument to an int for later use: The compiler (GCC version 4.2.4) returns the error: You can cast it to an intptr_t type. See also this documentation.. From and Into are generally intended to be lossless, infalliable conversions.as on the other hand can discard data and lead to bugs in some situations, for example casting a u64 to a usize may truncate the value on a 32-bit host. 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. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? 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. Java Type Casting - W3Schools SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); Why does flowing off the end of a non-void function without returning a value not produce a compiler error? Does Counterspell prevent from any further spells being cast on a given turn? 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. } SCAN_END_SINGLE(ATTR) ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] error: cast from 'void*' to 'int' loses precision - Stack Overflow STR34-C. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Already on GitHub? Projects. 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. Note the difference between the type casting of a variable and type casting of a pointer. ^~~~~~~~~~~~~~~~~~~~ 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. Making statements based on opinion; back them up with references or personal experience. 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 Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). 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). Thanks for contributing an answer to Stack Overflow! Hence there is no loss in data. then converted back to pointer to void, and the result will compare If not, check the pointer size on your platform, define these typedefs accordingly yourself and use them. What is the purpose of non-series Shimano components? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Notifications. If your standard library (even if it is not C99) happens to provide these types - use them. For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. use $(ARCHS_STANDARD_32_BIT) at Architecture instead of $(ARCHS_STANDARD). For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. Why is this sentence from The Great Gatsby grammatical? SCAN_PUT(ATTR, NULL); Find centralized, trusted content and collaborate around the technologies you use most. 10) A prvalue of type pointer to void (possibly cv-qualified) can be converted to pointer to any object type. Your first example is risky because you have to be very careful about the object lifetimes. Mutually exclusive execution using std::atomic? For example, the main thread could wait for all of the other threads to end before terminating. This will only compile if the destination type is long enough. */ >> -bool >> +enum conversion_safety >> unsafe_conversion_p (tree type, tree expr, bool . Again, all of the answers above missed the point badly. - the incident has nothing to do with me; can I use this this way? Connect and share knowledge within a single location that is structured and easy to search. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Casting type void to uint8_t - Arduino Forum C++ how to get the address stored in a void pointer? In Java, there are two types of casting: Widening Casting (automatically) - converting a smaller type to a larger type size. Bulk update symbol size units from mm to map units in rule-based symbology. Windows has 32 bit long only on 64 bit as well. warning C4311: 'type cast': pointer truncation from 'void *' to 'long' in ECPG test files. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Cast characters to unsigned char before converting to larger integer sizes Created by Robert Seacord, last modified by Jill Britton on Oct 03, 2022 Signed character data must be converted to unsigned char before being assigned or converted to a larger signed type. windows meson: cast to smaller integer type 'unsigned long' from 'void Disconnect between goals and daily tasksIs it me, or the industry? Cast a smaller integer to a larger integer - community - The Rust 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. To learn more, see our tips on writing great answers. The problem is not with casting, but with the target type loosing half of the pointer. You are correct, but cocos actually only uses that address as a unique id. The text was updated successfully, but these errors were encountered: This is memory reinterpretation - a completely unacceptable way to do what the OP is trying to do. This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. a cast of which the programmer should be aware of what (s)he is doing. windows meson: cast to 'HANDLE' (aka 'void *') from smaller integer Well occasionally send you account related emails. I need to cast the int from the first function so that I can use it as an argument for the second function. Note:You might receive a runtime exception if the pointer contains a value unsuitable for the context. 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 problem was there before, you just are being notified of it. Why does Mister Mxyzptlk need to have a weakness in the comics? Whats the grammar of "For those whose stories they are"? Does a summoned creature play immediately after being summoned by a ready action? vegan) just to try it, does this inconvenience the caterers and staff? The result is implementation-defined and typically yields the numeric address of the byte in memory that the pointer pointers to. 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. Why do academics stay as adjuncts for years rather than move around? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function.