How to use Clang static analyzer with a Cortex-M project? What is this brick with a round back and a stud on the side used for. d=(double *) Hi, Casting arguments inside the function is a lot safer. a cast of which the programmer should be aware of what (s)he is doing. In the realm of Android development, two languages have consistently stood out: Java and Kotlin. 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. Find centralized, trusted content and collaborate around the technologies you use most. Not the answer you're looking for? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. What is this brick with a round back and a stud on the side used for? 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. 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. I'm having a little bit of trouble regarding pointer casting in my program. #, Nov 14 '05 Wrong. So make sure you understand what you are doing! How to correctly cast a pointer to int in a 64-bit application? You use the address-of operator & to do that int x = 10; void *pointer = &x; And in the function you get the value of the pointer by using the dereference operator *: int y = * ( (int *) pointer); Share Improve this answer Follow edited Apr 15, 2013 at 13:58 answered Apr 15, 2013 at 13:53 Some programmer dude 396k 35 399 609 1 Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. When do you use in the accusative case? error: comparison between pointer and integer ('int' and 'string' (aka 'char *')), CS50 Caesar program is working but check50 says it isn't. 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). To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Asking for help, clarification, or responding to other answers. What you do here is undefined behavior, and undefined behavior of very practical sort. How to convert a factor to integer\numeric without loss of information? User without create permission can create a custom object from Managed package using Custom Rest API. I don't understand why the following two cases produce different Hi, I've this question: suppose we have two differently typed pointers: This is flat out wrong. The next Access Europe Meeting is on Wed 3 May 2023. To learn more, see our tips on writing great answers. Why does flowing off the end of a non-void function without returning a value not produce a compiler error? Connect and share knowledge within a single location that is structured and easy to search. A nit: in your version, the cast to void * is unnecessary. 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 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;. Again, all of the answers above missed the point badly. Thus as a result it may be less error prone to generate a pointer dynamcially and use that. A good thing in general, but if you want to disable the warning, just do it. (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. On most platforms pointers and longs are the same size, but ints and pointers often are not the same size on 64bit platforms. 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. 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. rev2023.3.3.43278. From that point on, you are dealing with 32 bits. Is there any known 80-bit collision attack? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. When is casting void pointer needed in C? Thanks for contributing an answer to Stack Overflow! And in this context, it is very very very common to see programmers lazily type cast the. For example, you might have an integer variable that you need to pass to a method whose parameter is typed as double. For more information, see How to safely cast using pattern matching and the as and is operators. 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. If your standard library (even if it is not C99) happens to provide these types - use them. Alternatively, if you choose to castthe ptr variableto (size_t) instead, then you don't need to worry about the pointer typeanymore. To learn more, see our tips on writing great answers. The casting operators (int) and (double) are used right next to a number or variable to create a temporary value converted to a different data type. Usually that means the pointer is allocated with. @ok Question is, how do I explain this to Clang? And, most of these will not even work on gcc4. 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 can I find a clear diagram of the SPECK algorithm? even though the compiler doesn't know you only ever pass myFcn to pthread_create in conjunction with an integer. If the sizes are different then endianess comes into play. I think using intptr_t is the correct intermediate here, since it's guaranteed to be large enough to contain the integral value of the void*, and once I have an integer value I can then truncate it without causing the compiler to complain. Save this piece of code as mycast.hpp and add -include mycast.hpp to your Makefile. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. I saw on a couple of recent posts people saying that casting the return The semantics of numeric casts are: Casting between two integers of the same size (e.g. I agree passing a dynamically allocated pointer is fine (and I think the best way). 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. Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey. 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. Did the Golden Gate Bridge 'flatten' under the weight of 300,000 people in 1987? Boolean algebra of the lattice of subspaces of a vector space? Pros: The problem with C casts is the ambiguity of the operation; sometimes you are doing a conversion (e.g., (int)3.5) and sometimes you are doing a cast (e.g., (int)"hello"); C++ casts avoid this. 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. If the types are from the same inheritance tree, then you should either use dynamic_casts or even better, you should benefit from dynamic dispatching.. dynamic_cast is slightly better, but still should be avoided. User without create permission can create a custom object from Managed package using Custom Rest API. comment:4 by Kurt Schwehr, 8 years ago r28216 removes OGDIDataset:: GetInternalHandle from trunk By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Does a password policy with a restriction of repeated characters increase security? Can I use an 11 watt LED bulb in a lamp rated for 8.6 watts maximum? You need to pass an actual pointer. If you need to keep the returned address, just keep it as void*. Generating points along line with specifying the origin of point generation in QGIS. For example, assigning an int value to a long variable. 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. Were sorry. For integral types, this means the range of the source type is a proper subset of the range for the target type. The compiler is perfectly correct & accurate! Canadian of Polish descent travel to Poland with Canadian passport, Two MacBook Pro with same model number (A1286) but different year, Folder's list view has different sized fonts in different folders. Did the Golden Gate Bridge 'flatten' under the weight of 300,000 people in 1987? Can you still use Commanders Strike if the only attack available to forego is an attack against an ally? C / C++ Forums on Bytes. */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; Remembering to delete the pointer after use so that we don't leak. The problem is not with casting, but with the target type loosing half of the pointer. So reinterpret_cast has casted it to long type and then static_cast safely casts long to int, if you are ready do truncte the data. I would like to know the reason. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. 1) zero or one conversion from the following set: lvalue-to-rvalue conversion, array-to-pointer conversion, and function-to-pointer conversion; 2) zero or one numeric promotion or numeric conversion; 3) zero or one function pointer conversion; (since C++17) 4) zero or one qualification conversion. 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. Since gcc compiles that you are performing arithmetic between void* and an int (1024). 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. To disable or enable advertisements and analytics tracking please visit the manage ads & tracking page. There's no proper way to cast this to int in general case. Solution 1. Why did DOS-based Windows require HIMEM.SYS to boot? Explicitly call a single-argument constructor or a conversion operator. "Signpost" puzzle from Tatham's collection. Embedded hyperlinks in a thesis or research paper. If the result lies outside the range of representable values by the type, the conversion causes, Otherwise, if the conversion is between numeric types of the same kind (integer-to-integer or floating-to-floating), the conversion is valid, but the value is. 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. By using Bytes.com and it's services, you agree to our Privacy Policy and Terms of Use. Run this code to find how Java handles division and what casting can do to the results.

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