*/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. If any, how can the original function works without errors if we just ignore the warning. to the original pointer: The following type designates an unsigned integer type with the Asking for help, clarification, or responding to other answers. I can easily imagine a situation where rewriting code using, Disabling "cast from pointer to smaller type uint32_t" error in Clang, https://github.com/llvm-mirror/clang/blob/release_50/include/clang/Basic/DiagnosticSemaKinds.td#L6193, https://github.com/llvm-mirror/clang/blob/release_50/lib/Sema/SemaCast.cpp#L2112, How a top-ranked engineering school reimagined CS curriculum (Ep. Has the cause of a rocket failure ever been mis-identified, such that another launch failed due to the same problem? It's not them. The following program casts a double to an int. Making statements based on opinion; back them up with references or personal experience. is there such a thing as "right to be heard"? Canadian of Polish descent travel to Poland with Canadian passport. 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). I have a question about casting a function pointer. Can I use the spell Immovable Object to create a castle which floats above the clouds? Was Aristarchus the first to propose heliocentrism? 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;. C / C++ Forums on Bytes. You are getting warnings due to casting a void* to a type of a different size. dynamic, and reinterpret casting. However, you are also casting the result of this operation to (void*). Since gcc compiles that you are performing arithmetic between void* and an int (1024). Without RTTI your code will be cleaner | Sandor Dargo's Blog If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . Two MacBook Pro with same model number (A1286) but different year. static const void* M_OFFSET = (void*)64*1024; Since gcc compiles that you are performing arithmetic between void* and an int ( 1024 ). The Test method has an Animal parameter, thus explicitly casting the argument a to a Reptile makes a dangerous assumption. Is "I didn't think it was serious" usually a good defence against "duty to rescue"? Does it effect my blogs SEO rankings? If your standard library (even if it is not C99) happens to provide these types - use them. Offline ImPer Westermark over 12 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. Syntax static_cast< new-type > ( expression ) Returns a value of type new-type . The only. You may declare a const int variable and cast its reference to the void*. If the data types are compatible, then Java will perform the conversion automatically known as Automatic Type Conversion, and if not then they need to be cast or converted explicitly. How can I control PNP and NPN transistors together from one pin? "Signpost" puzzle from Tatham's collection. Explanation Only the following conversions can be done with static_cast, except when such conversions would cast away constness or volatility . It's always a good practice to put your #define's in brackets to avoid such surprise. 565), Improving the copy in the close modal and post notices - 2023 edition, New blog post from our CEO Prashanth: Community is the future of AI. a generic module (say some ADT implementation) that requires a by: William S Fulton |
this way I convert an int to a void* which is much better than converting a void* to an int. Why are players required to record the moves in World Championship Classical games? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. In this case, casting the pointer back to an integer is meaningless, because . MIP Model with relaxed integer constraints takes longer to solve than normal model, why? While working with Threads in C, I'm facing the warning, "warning: cast to pointer from integer of different size". error: comparison between pointer and integer ('int' and 'string' (aka 'char *')), CS50 Caesar program is working but check50 says it isn't. The error message mentions the diagnostic responsible for error message, e.g. ), For those who are interested. This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s). By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. @DavidHeffernan, sane thread APIs wouldn't send integral data to the thread procedures, they would send pointers. How to correctly cast a pointer to int in a 64-bit application? The error I'm getting is: error: cast from pointer to smaller type 'uint32_t' (aka 'unsigned int') loses information. 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. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. Most answers just try to extract 32 useless bits out of the argument. Going through them one by one would be very tedious and since this is an experimental project anyway, I'm happy to settle for a "hackish" workaround. Asking for help, clarification, or responding to other answers. @Xax: Here's a fixed version, without the race condition: gist.github.com/depp/241d6f839b799042c409, gist.github.com/depp/3f04508a88a114734195, How a top-ranked engineering school reimagined CS curriculum (Ep. One could try -fms-extensions (hopefully not -fms-compatibility), but that would bring all the shebang with it. Don't do that. Interpreting non-statistically significant results: Do we have "no evidence" or "insufficient evidence" to reject the null? Infact I know several systems where that does not hold. Episode about a group who book passage on a space ship controlled by an AI, who turns out to be a human who can't leave his ship? Not the answer you're looking for? Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, "what happen when typcating normal variable to void* or any pointer variable?" Thanks for pointing that out. Generating points along line with specifying the origin of point generation in QGIS. some reading around on it and why it is sometimes used. eg. Put your define inside a bracket: without a problem. For built-in numeric types, an implicit conversion can be made when the value to be stored can fit into the variable without being truncated or rounded off. Visit Microsoft Q&A to post new questions. How can I control PNP and NPN transistors together from one pin? @BlueMoon Thanks a lot! That could create all kinds of trouble. Connect and share knowledge within a single location that is structured and easy to search. Just because you're altering. Not the answer you're looking for? Hello, I am currently working on a UDF for the heterogeneous reaction using it to describe a simple equilibrium model using the Antoine equation and vapor pressure. 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. casting from int to void* and back to int. Can I use an 11 watt LED bulb in a lamp rated for 8.6 watts maximum? What is the symbol (which looks similar to an equals sign) called? X* px = new X; The most general answer is - in no way. LLNL's tutorial is bad and they should feel bad. Can my creature spell be countered if I cast a split second spell after it? This code is a bit odd (but a void* can certainly host a int on all architectures on which GDAL can be compiled), and certainly unused by anyone, so you could just remove the GetInternalHandle () implementation as well if you prefer. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. What is this brick with a round back and a stud on the side used for? Posted on Author Author Half your pointer will be garbage. 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. I have read in one of old posting that don't cast of pointer which If so, is Why does flowing off the end of a non-void function without returning a value not produce a compiler error? Keep in mind that thrArg should exist till the myFcn() uses it. 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). It's an int type guaranteed to be big enough to contain a pointer. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. Save this piece of code as mycast.hpp and add -include mycast.hpp to your Makefile. Why does setupterm terminate the program? BUT converting a pointer to void* and back again is well supported (everywhere). There is no "correct" way to store a 64-bit pointer in an 32-bit integer. I would create a structure and pass that as void* to pthread_create. More info about Internet Explorer and Microsoft Edge, How to convert between hexadecimal strings and numeric types, How to safely cast using pattern matching and the as and is operators. Is "I didn't think it was serious" usually a good defence against "duty to rescue"? For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey. Did the Golden Gate Bridge 'flatten' under the weight of 300,000 people in 1987? /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. I agree passing a dynamically allocated pointer is fine (and I think the best way). Clang warnings for an invalid casting? - The FreeBSD Forums How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. Is there any known 80-bit collision attack? Since the culprit is probably something like -Wall which enables many warnings you should keep on, you should selectively disable this single warning. OP said he doesn't want it. Usually that means the pointer is allocated with. How to set, clear, and toggle a single bit? This is a fine way to pass integers to new pthreads, if that is what you need. Just edited. If your code has the chance to ever be ported to some platform where this doesn't hold, this won't work. pointer/reference to a derived class pointer/reference. I am compiling this program in linux gcc compiler.. For more information, see User-defined conversion operators. Connect and share knowledge within a single location that is structured and easy to search. To learn more, see our tips on writing great answers. -1, Uggh. It does not because. cast to void *' from smaller integer type 'int The next Access Europe Meeting is on Wed 3 May 2023. @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. When is casting void pointer needed in C? dynamic_cast safely converts pointers and references to classes up, down and sideways along the inheritance hierarchy - according to CppReference. How to force Unity Editor/TestRunner to run at full speed when in background? LettuceConnectionFactory was destroyed and cannot be used - CSDN You are just making it bigger by tricking the compiler and the ABI. However, this specific error is not due to a warning and I can't find any option to disable errors (makes sense, since most errors are fatal). 1.6. Casting and Ranges of Variables AP CSAwesome For example, you might have an integer variable that you need to pass to a method whose parameter is typed as double. even though the compiler doesn't know you only ever pass myFcn to pthread_create in conjunction with an integer. To learn more, see our tips on writing great answers. 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. As Ferruccio said, int must be replaced with intptr_t to make the program meaningful. cast to void *' from smaller integer type 'int-tdecu credit scoretdecu credit score The following program casts a double to an int. Unfortunately, that hardware is 64-bit and the code contains many instances of pointer arithmetic that expects pointers to be 32-bit, i.e. then converted back to pointer to void, and the result will compare If a negative integer value is converted to an unsigned type, the resulting value corresponds to its 2's complement bitwise representation (i.e., If the conversion is from a floating-point type to an integer type, the value is truncated (the decimal part is removed). In 64-bit programs, the size of the pointer is 64 bits and it cannot be put into the int type that remains 32-bit almost in all the systems. Did the drapes in old theatres actually say "ASBESTOS" on them? error: request for member '..' in '..' which is of non-class type. Explicitly call a single-argument constructor or a conversion operator. Wrong. The content you requested has been removed. I assumed that gcc makes a 65536 out of my define, but I was wrong. comment:4 by Kurt Schwehr, 8 years ago r28216 removes OGDIDataset:: GetInternalHandle from trunk Find centralized, trusted content and collaborate around the technologies you use most. Is a downhill scooter lighter than a downhill MTB with same performance? To learn more, see our tips on writing great answers. c - type casting integer to void* - Stack Overflow How to correctly cast a pointer to int in a 64-bit application? Why don't we use the 7805 for car phone chargers? So instead I modified the implementation of malloc to ensure it never allocates memory above the 4GB limit. Folder's list view has different sized fonts in different folders. 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. You can use any other pointer, or you can use (size_t), which is 64 bits. What differentiates living as mere roommates from living in a marriage-like relationship? If the sizes are different then endianess comes into play. Because C# is statically-typed at compile time, after a variable is declared, it cannot be declared again or assigned a value of another type unless that type is implicitly convertible to the variable's type. But to just truncate the integer value and not having to fix all the wrong uses of uint32_t just yet, you could use static_cast(reinterpret_cast(ptr)). For more information, see How to safely cast using pattern matching and the as and is operators. Say I want to make 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.
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