Not the answer you're looking for? The main point is: a pointer has a platform dependent size. @DavidHeffernan, sane thread APIs wouldn't send integral data to the thread procedures, they would send pointers. It's an int type guaranteed to be big enough to contain a pointer. you can just change architecture to support 32 bit compilation by all below in in Build Settings. ", "? Usually that means the pointer is allocated with. The problem is not with casting, but with the target type loosing half of the pointer. And in this context, it is very very very common to see programmers lazily type cast the. If your standard library (even if it is not C99) happens to provide these types - use them. If not, check the pointer size on your platform, define these typedefs accordingly yourself and use them. To learn more, see our tips on writing great answers. STR34-C. Projects. How to use Slater Type Orbitals as a basis functions in matrix method correctly? Find centralized, trusted content and collaborate around the technologies you use most. What does it mean to convert int to void* or vice versa? (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. 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;. this way you won't get any warning. Identify those arcade games from a 1983 Brazilian music video. But this code pass the normal variable .. ncdu: What's going on with this second size column? But, sure, in that specific case you can pass a local variable address, type casting integer to void* [duplicate]. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Remembering to delete the pointer after use so that we don't leak. I agree passing a dynamically allocated pointer is fine (and I think the best way). No sense in writing a few dozen lines of extra code just to get a bunch of numbered threads. While working with Threads in C, I'm facing the warning, "warning: cast to pointer from integer of different size". How do I check if a string represents a number (float or int)? Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj Thanks. . It is done by the compiler on its own, without any external trigger from the user. Please help me compile Chez Scheme. Star 675. As with all cast expressions, the result is: Two objects a and b are pointer-interconvertible if: static_cast may also be used to disambiguate function overloads by performing a function-to-pointer conversion to specific type, as in. My code is all over the place now but I appreciate you all helping me on my journey to mastery! 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. 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. Implementation-dependent. ^~~~~~~~~~~~~~~~~~~~~ Does Counterspell prevent from any further spells being cast on a given turn? -1, Uggh. How can this new ban on drag possibly be considered constitutional? To learn more, see our tips on writing great answers. 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). This is flat out wrong. itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" Why is there a voltage on my HDMI and coaxial cables? 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. 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. How do I work around the GCC "error: cast from SourceLocation* to int loses precision" error when compiling cmockery.c? then converted back to pointer to void, and the result will compare Difficulties with estimation of epsilon-delta limit proof. rev2023.3.3.43278. If your standard library (even if it is not C99) happens to provide these types - use them. Offline ImPer Westermark over 11 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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). 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. Put your define inside a bracket: without a problem. equal to the original pointer: First you are using a define, which is not a variable. This is what the second warning is telling you. Why do academics stay as adjuncts for years rather than move around? How to tell which packages are held back due to phased updates, Identify those arcade games from a 1983 Brazilian music video. Half your pointer will be garbage. for (i=0, j=0; j=sizeof(int). 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. In Java, there are two types of casting: Widening Casting (automatically) - converting a smaller type to a larger type size. . And, most of these will not even work on gcc4. For example, the main thread could wait for all of the other threads to end before terminating. But gcc always give me a warning, that i cannot cast an int to a void*. Otherwise, if the original pointer value points to an object a, and there is an object b of the . Update: Today, i download the latest version of cocos2d-x (cocos2d-x 2.2.3). This is not even remotely "the correct answer". Disconnect between goals and daily tasksIs it me, or the industry? You can use any other pointer, or you can use (size_t), which is 64 bits. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. How to use Slater Type Orbitals as a basis functions in matrix method correctly? You are getting warnings due to casting a void* to a type of a different size. Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. "-I.." "-Iinclude\openflow" "-I..\include\openflow" "-Iinclude\openvswitch" "-I..\include\openvsw long guarantees a pointer size on Linux on any machine. Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. 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. 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. } SCAN_END_SINGLE(ATTR) 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. "I think what you should do is actually pass the address of the variable to the function" Not necessarily. ^~~~~~~~~~~~~~~~~~~~ This forum has migrated to Microsoft Q&A. The preprocesor absolutely will not perform arithmetic. windows meson: cast to smaller integer type 'unsigned long' from 'void *'. ^~~~~~~~~~~~~~~~~~~~ a cast of which the programmer should be aware of what (s)he is doing. A long long would not work for 32bit systems and a long would not work for 64 bit Windows (while 64bit Unix and Unix-like systems like OS X use the LP64 data model, in which a long is 64bit, 64bit Windows uses the LLP64 data model, in which a long has a size of 32bit (http://en.wikipedia.org/wiki/64-bit_computing#64-bit_data_models)). 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. You can convert the values from one type to another explicitly using the cast operator as follows (type_name) expression 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. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. Any help with this is appreciated. Using an integer address (like &x) is probably wrong, indeed each modification you will execute on x will affect the pass behaviour. 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. Connect and share knowledge within a single location that is structured and easy to search. @Shahbaz you could but I will not suggest to a C newbie to use globals. returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); this way I convert an int to a void* which is much better than converting a void* to an int. An object pointer (including void*) or function pointer can be converted to an integer type using reinterpret_cast. This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. 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. static_cast on the other hand should deny your stripping away the const qualifier. */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. 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. To be honest, I think, clang is too restrictive here. */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. 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. I'm using cocos2d-x-2.2.2. Why does Mister Mxyzptlk need to have a weakness in the comics? I assumed that gcc makes a 65536 out of my define, but I was wrong. Taking the above declarations of A, D, ch of the . 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. @LearnCocos2D: so, how can i "overcome" the error without editing any not-my-code or in-library-file lines? Find centralized, trusted content and collaborate around the technologies you use most. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? How to convert a factor to integer\numeric without loss of information? Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul 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; In the case of Widening Type Casting, the lower data type (having smaller size) is converted into the higher data type (having larger size). eg. Disconnect between goals and daily tasksIs it me, or the industry? A nit: in your version, the cast to void * is unnecessary. 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). 471,961 Members | 900 Online. So you know you can cast it back like this. Thanks for contributing an answer to Stack Overflow! XCode 5.1 is change all architecture to 64 bit. For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. But I don't want to edit code in "EAGLView.mm" because it's a "library file". Asking for help, clarification, or responding to other answers. Yeah, the tutorial is doing it wrong. Does Counterspell prevent from any further spells being cast on a given turn? Is it suspicious or odd to stand by the gate of a GA airport watching the planes? Not the answer you're looking for? 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. It's always a good practice to put your #define's in brackets to avoid such surprise. RNINGS" "-D_CRT_SECURE_NO_DEPRECATE" -MD -MQ lib/libopenvswitch.a.p/odp-util.c.obj -MF "lib\libopenvswitch.a.p\odp-util.c.obj.d" -o lib/libopenvswitch.a.p/od Converting a void* to an int is non-portable way that may work or may not! By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' Converting one datatype into another is known as type casting or, type-conversion. 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. Returns a value of type new-type. @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. How to use Slater Type Orbitals as a basis functions in matrix method correctly? The result is the same as implicit conversion from the enum's underlying type to the destination type. Is a PhD visitor considered as a visiting scholar. As Ferruccio said, int must be replaced with intptr_t to make the program meaningful. converted back to pointer to void, and the result will compare equal How do I force make/GCC to show me the commands? Connect and share knowledge within a single location that is structured and easy to search. reinterpret_cast is a type of casting operator used in C++. The program can be set in such a way to ask the user to inform the type of data and . How do I count the number of sentences in C using ". In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. What is the purpose of non-series Shimano components? Using Kolmogorov complexity to measure difficulty of problems? Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. I cannot reverse my upvote of user384706's answer, but it's wrong. Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. Create an account to follow your favorite communities and start taking part in conversations. C++ how to get the address stored in a void pointer? 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. It was derived from the BCPL, and the name of the b language is possibly from the BCPL contraction. Recovering from a blunder I made while emailing a professor. ncdu: What's going on with this second size column? 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. Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. Use #include to define it. And then assign it to the double variable. For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. If this is the data to a thread procedure, then you quite commonly want to pass by value. 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. Error while setting app icon and launch image in xcode 5.1. From what I read about casting in the C11 standard, my feeling is, that it is arguable to emit a warning on an explicit conversion. property that any valid pointer to void can be converted to this type, What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. A missing cast in the new fast > enumeration code. cast operators [edit] When an expression is used in the context where a value of a different type is expected, conversionmay occur: intn =1L;// expression 1L has type long, int is expectedn =2.1;// expression 2.1 has type double, int is expectedchar*p =malloc(10);// expression malloc(10) has type void*, char* is expected Casting a pointer to void* and back is valid use of reinterpret_cast<>. 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 just occur with Xcode 5.1. GitHub Skip to content Product Solutions Open Source Pricing Sign in Sign up smadaminov / ovs-dpdk-meson-issues Public Notifications Fork 1 Star 1 Code Issues 66 Pull requests Actions Projects 1 Security Insights New issue We have to pass address of the variable to the function because in function definition argument is pointer variable. GitHub. (i.e. You can fix this error by replacing this line of code. The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function. The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS. Yesterday, I updated Xcode to the newest version (5.1 (5B130a)) to compatible with iOS 7.1. Since gcc compiles that you are performing arithmetic between void* and an int (1024). Why do small African island nations perform better than African continental nations, considering democracy and human development? 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.