The text was updated successfully, but these errors were encountered: You signed in with another tab or window. The most general answer is - in no way. To be honest, I think, clang is too restrictive here. 7.1 New Cast Operations The C++ standard defines new cast operations that provide finer control than previous cast operations. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? 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. This solution is in accordance with INT18-C. 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. itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" Where does this (supposedly) Gibson quote come from? Please help me compile Chez Scheme. (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. Any help with this is appreciated. Anw, the project still build and run normally when i use Xcode 5.0 with iOS 7.0. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. Api says this is how i should create thread: So if I want to pass an int what I think I should do is: The second example assumes that a pointer is wide enough to store an int. Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. 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; It modifies >> Wconversion-real.c, Wconversion-real-integer.c and pr35635.c to be more >> specific > > If the patch passes existing tests, I'd be inclined to leave them > tests alone and add new ones that are specific to what this patch > changes. Why is there a voltage on my HDMI and coaxial cables? This is why you got Error 1 C2036, from your post. @LearnCocos2D: so, how can i "overcome" the error without editing any not-my-code or in-library-file lines? What does casting to void* does when passing arguments to variadic functions? I don't see how anything bad can happen . ncdu: What's going on with this second size column? How to get the error message from the error code returned by GetLastError()? Can I tell police to wait and call a lawyer when served with a search warrant? There is absolutely not gurantee that sizeof(int) <= sizeof(void*). An object pointer (including void*) or function pointer can be converted to an integer type using reinterpret_cast. It was derived from the BCPL, and the name of the b language is possibly from the BCPL contraction. Therefore it is perfectly valid for the compiler to throw an error for a line like. windows meson: cast to smaller integer type 'unsigned long' from 'void *'. @DavidHeffernan I rephrased that sentence a little. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. "-D_FILE_OFFSET_BITS=64" "-Wall" "-Winvalid-pch" "-g" "-Wthread-safety" "-Wno-microsoft-enum-forward-reference" "-Wno-unused-function" "-Wno-sometimes-unini 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. To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. Identify those arcade games from a 1983 Brazilian music video. Windows has 32 bit long only on 64 bit as well. LLNL's tutorial is bad and they should feel bad. (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. As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). Star 675. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Making statements based on opinion; back them up with references or personal experience. 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; to the original pointer: The following type designates an unsigned integer type with the What is the point of Thrower's Bandolier? Issues. for saving RAM), use union, and make sure, if the mem address is treated as an int only if you know it was last set as an int. ", "!"? C++ how to get the address stored in a void pointer? rev2023.3.3.43278. Projects. then converted back to pointer to void, and the result will compare It's always a good practice to put your #define's in brackets to avoid such surprise. ), Styling contours by colour and by line thickness in QGIS. You think by casting it here that you are avoiding the problem! Thank you all for your feedback. How do I align things in the following tabular environment? Thus as a result it may be less error prone to generate a pointer dynamcially and use that. vegan) just to try it, does this inconvenience the caterers and staff? 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. actually no, as int my be a smaller type than a pointer ;-) But, of course with int64_t it works fine. I'm trying to create a void* from an int. On many systems, an 8-bit unsigned int can be stored at any address while an unsigned 32-bit int must be aligned on an address that is a multiple of 4. p-util.c.obj "-c" ../lib/odp-util.c And when assigning to a void pointer, all type information is lost. 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. */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); for (i=0, j=0; j returnPtr[j] = (void *) (ptr + i); // <<< Compile Errors, Error1error C2036: 'void *' : unknown sizec:\temp\testone\lib\utils.c57, 2> returnPtr[j] = (void *) ((long*)ptr + i); // <<< No compile errors, 3> returnPtr[j] = (void *) ((char*)ptr + i); // <<< No compile errors. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Keep in mind that thrArg should exist till the myFcn() uses it. 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. ../lib/odp-util.c:5489:33: note: expanded from macro 'SCAN_PUT_ATTR' Find centralized, trusted content and collaborate around the technologies you use most. If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . 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. LLNL's tutorial is bad and they should feel bad. 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. Thanks. How can this new ban on drag possibly be considered constitutional? . Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? 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. Please tell me error: cast from 'void*' to 'int' loses precision, How Intuit democratizes AI development across teams through reusability. 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. ^~~~~~~~~~~~~~~~~~~~ Note the difference between the type casting of a variable and type casting of a pointer. Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. Narrowing Casting (manually) - converting a larger type to a . (int) pthread_self() 64int48intuintptr_t (unsigned int) You use the address-of operator & to do that. I'm trying to learn pthreads and thing that keeps bugging me is how do i really pass argument to the function. I assumed that gcc makes a 65536 out of my define, but I was wrong. Do new devs get fired if they can't solve a certain bug? Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? If you are going to pass the address you typically need to exert some more control over the lifetime of the object. Does a summoned creature play immediately after being summoned by a ready action? Hence there is no loss in data. pthread create managing values generated in function (in c), Establishing TCP socket connection between PHP client and C server on Ubuntu. I have a function with prototype void* myFcn(void* arg) which is used as the starting point for a pthread. Error while setting app icon and launch image in xcode 5.1. and how to print the thread id of 2d array argument? If the object expression refers or points to is actually a base class subobject of an object of type D, the result refers to the enclosing object of type D. Otherwise, the behavior is undefined: When the target type is bool (possibly cv-qualified), the result is false if the original value is zero and true for all other values. Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. How to notate a grace note at the start of a bar with lilypond? Wrong. The bigint data type is intended for use when integer values might exceed the range that is supported by the int data type.. bigint fits between smallmoney and int in the data type precedence chart.. While working with Threads in C, I'm facing the warning, "warning: cast to pointer from integer of different size". Even though what you say regarding the lifetime of the object is true, integral types are too limited for a generic API. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. All character types are to be converted to an integer. Converts between types using a combination of implicit and user-defined conversions. The following behavior-changing defect reports were applied retroactively to previously published C++ standards. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? : iPhone Retina 4-inch 64-bit) is selected. Thanks for pointing that out. Visit Microsoft Q&A to post new questions. The difference between the phonemes /p/ and /b/ in Japanese. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ How Intuit democratizes AI development across teams through reusability. There's no proper way to cast this to int in general case. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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; My code is all over the place now but I appreciate you all helping me on my journey to mastery! Thanks for contributing an answer to Stack Overflow! Create an account to follow your favorite communities and start taking part in conversations. How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. Even if you are compiling your program for a 32-bit computer, you should fix your code to remove these warnings, to ensure your code is easily portable to 64-bit. 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. 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;. How do I count the number of sentences in C using ". Yesterday, I updated Xcode to the newest version (5.1 (5B130a)) to compatible with iOS 7.1. Most answers just try to extract 32 useless bits out of the argument. Functions return bigint only if the parameter expression is a bigint data type. As a result of the integer division 3/2 we get the value 1, which is of the int type. You are getting warnings due to casting a void* to a type of a different size. 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 a PhD visitor considered as a visiting scholar. @jackdoe: It's a waste of human life to write code that "you may need in the future". 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. use $(ARCHS_STANDARD_32_BIT) at Architecture instead of $(ARCHS_STANDARD). But the problem has still happened. 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 ) To learn more, see our tips on writing great answers. -1, Uggh. In C (int)b is called an explicit conversion, i.e. If the sizes are different then endianess comes into play. You are just making it bigger by tricking the compiler and the ABI. how to cascade 2d int array to 2d void pointer array? Offline ImPer Westermark over 11 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; Implementation-dependent. Yeah, the tutorial is doing it wrong. 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). In Java, there are two types of casting: Widening Casting (automatically) - converting a smaller type to a larger type size. 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. This is a fine way to pass integers to new pthreads, if that is what you need. Not the answer you're looking for? Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). Find centralized, trusted content and collaborate around the technologies you use most. The problem just occur with Xcode 5.1. 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. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? this question. 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. Connect and share knowledge within a single location that is structured and easy to search. SCAN_PUT_ATTR(key, ATTR, skey, FUNC); Note that it's not guaranteed that casting an, Generally this kind of type casting does not lead to any concern as long as the addresses are encoded using the same length as the "variable type" (. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' Well it does this because you are converting a 64 bits pointer to an 32 bits integer so you loose information. Disconnect between goals and daily tasksIs it me, or the industry? This page has been accessed 1,655,678 times. The cast back to int * is not, though. Otherwise, if the original pointer value points to an object a, and there is an object b of the . Making statements based on opinion; back them up with references or personal experience. For integer casts in specific, using into() signals that . a cast of which the programmer should be aware of what (s)he is doing. 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. Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. What is the point of Thrower's Bandolier? What I am saying is that it would be safer to use new(5) rather than 5 and deal with it appropriately at the other end. Connect and share knowledge within a single location that is structured and easy to search. I agree passing a dynamically allocated pointer is fine (and I think the best way). ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' The preprocessor will replace your code by this: This is unlikely what you are trying to do. 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. To learn more, see our tips on writing great answers. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. B language was designed to develop . Why do small African island nations perform better than African continental nations, considering democracy and human development? You can also convert values from one type to another explicitly using the cast operator (see Chapter 5 ): ( type_name) expression In the following example, the cast operator causes the division of one integer variable by another to be performed as a floating-point operation: int sum = 22, count = 5; double mean = (double)sum / count; 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. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. A void pointer can be really useful if the programmer is not sure about the data type of data inputted by the end user. Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul This is not even remotely "the correct answer". The mapping in pointer<->integer casts is implementation defined, but the intent was that if the pointer type is large enough and isn't forcefully aligned (, But that's different. Mutually exclusive execution using std::atomic? Implementing From will result in the Into implementation but not vice-versa. The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. Use #include to define it. XCode 5.1 is change all architecture to 64 bit. Instead of using a long cast, you should cast to size_t. If the destination type is bool, this is a boolean conversion (see below). That's not a good idea if the original object (that was cast to void*) was an integer. Then i can continue compiling. Can Martian regolith be easily melted with microwaves? So,solution #3 works just fine. Why is this sentence from The Great Gatsby grammatical? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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 . Asking for help, clarification, or responding to other answers. ), For those who are interested. 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 . But gcc always give me a warning, that i cannot cast an int to a void*. SQL Server does not automatically promote . The problem was there before, you just are being notified of it. I need to cast the int from the first function so that I can use it as an argument for the second function. You can only do this if you use a synchronization primitive to ensure that there is no race condition. Put your define inside a bracket: without a problem. But I don't want to edit code in "EAGLView.mm" because it's a "library file". Don't do that. Basically its a better version of (void *)i. GitHub. 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. Press question mark to learn the rest of the keyboard shortcuts. How can this new ban on drag possibly be considered constitutional? How Intuit democratizes AI development across teams through reusability. What is the purpose of non-series Shimano components? ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] However the actual code in question contains an explicit c-style cast to int. Update: Today, i download the latest version of cocos2d-x (cocos2d-x 2.2.3). There is no "correct" way to store a 64-bit pointer in an 32-bit integer. Can Martian regolith be easily melted with microwaves? The preprocesor absolutely will not perform arithmetic. Java Type Casting. You may declare a const int variable and cast its reference to the void*. The value of float variable is= 37.75. SCAN_PUT(ATTR, NULL); Any expression can be cast to type void (which means that the result of the expression is ignored), but it's not legal to cast an expression of type void to type int not least because the result of such a cast wouldn't make any sense. Don't do that. He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. The calculated expression consists of two operations. This will get you a pointer from a 32 bit offset: A function pointer is incompatible to void* (and any other non function pointer). Once you manage to make this cast, then what?! The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS. A cast specifies a conversion from one type to another. The pointer doesn't actually point to anything, but it's the result of an earlier cast from an integer to a pointer (e.g. How do I force make/GCC to show me the commands? Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Setting a buffer of char* with intermediate casting to int*. Not the answer you're looking for? 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. If any, how can the original function works without errors if we just ignore the warning. Mutually exclusive execution using std::atomic? 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. You can use any other pointer, or you can use (size_t), which is 64 bits. Note:You might receive a runtime exception if the pointer contains a value unsuitable for the context. Making statements based on opinion; back them up with references or personal experience. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. Half your pointer will be garbage. If you do this, you have the thread reference a value that (hopefully still) lives in some other thread. I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . I have looked around and can't seem to find any information on how to do this. 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). @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. From the question I presume the OP does. If you need to keep the returned address, just keep it as void*. to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj Only the following conversions can be done with static_cast, except when such conversions would cast away constness or volatility. this way I convert an int to a void* which is much better than converting a void* to an int. Pd = Pa; Similarly, Pc may be type cast to type int and assigned the value Pa. 1.