By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Why is there a voltage on my HDMI and coaxial cables? Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul Do new devs get fired if they can't solve a certain bug? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. You use the address-of operator & to do that. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Making statements based on opinion; back them up with references or personal experience. B programing language is a language based on basic combined programming or a BCPL, and it is the precursor of the C programming language. And, most of these will not even work on gcc4. What happens if you typecast as unsigned first? 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. // OK: lvalue denoting the original d object, // UB: the b subobject is not a base class subobject, // 6. array-to-pointer followed by upcast, https://en.cppreference.com/mwiki/index.php?title=cpp/language/static_cast&oldid=147983, when converting a 'pointer to object' to 'pointer to, the conversion from floating-point values, the conversion from bit-fields to rvalue references, the conversion from integral or enumeration values to enumeration, the conversion from integral or enumeration values to, the conversion from a member of base class type to, a standard-layout class object with no data members, a non-standard-layout union object and a non-static data, for base-to-derived pointer conversions and, the conversion to enumeration types with fixed underlying type, a standard-layout class might have a non-pointer-interconvertible, If the underlying type is not fixed, the behavior is undefined if the value of, If the underlying type is fixed, the result is the same as, one is a union object and the other is a non-static data member of that object, or. It solved my problem too. This solution is in accordance with INT18-C. Keep in mind that thrArg should exist till the myFcn() uses it. But assuming that it is, as long as the caller and the callee agree, you can do that sort of thing. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. C/C++ , Cerror: cast to 'void *' from smaller integer type 'int'. @LearnCocos2D: so, how can i "overcome" the error without editing any not-my-code or in-library-file lines? You should perform type conversion based on 64bit build system because the type "int" supports only -32768 ~ 32768. *PATCH] platform/x86: hp-wmi: Fix cast to smaller integer type warning @ 2023-01-23 13:28 Hans de Goede 2023-01-23 13:56 ` Hans de Goede 0 siblings, 1 reply; 2+ messages in thread From: Hans de Goede @ 2023-01-23 13:28 UTC (permalink / raw) To: Mark Gross Cc: Hans de Goede, Andy Shevchenko, platform-driver-x86, kernel test robot Fix the following . (int) pthread_self() 64int48intuintptr_t (unsigned int) What is the purpose of non-series Shimano components? ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. I think the solution 3> should be the correct one. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Asking for help, clarification, or responding to other answers. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Already on GitHub? You are correct, but cocos actually only uses that address as a unique id. The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function. 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. windows meson: cast to smaller integer type 'unsigned long' from 'void *'. There exist two main syntaxes for generic type-casting: functional and c-like: 1 2 3 4 double x = 10.3; int y; y = int (x); // functional notation y = (int) x; // c-like cast notation The functionality of these generic forms of type-casting is enough for most needs with fundamental data types. 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 394k 35 393 602 1 Usually that means the pointer is allocated with. A nit: in your version, the cast to void * is unnecessary. @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. 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. In the best case this will give the same results as the original code, with no advantages, but in the worst case it will fail in multiple catastrophic ways (type punning, endianness, less efficient, etc. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? rev2023.3.3.43278. void* -> integer -> void* rather than integer -> void* -> integer. Issues. ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. To learn more, see our tips on writing great answers. The only exception is exotic systems with the SILP64 data model, where the size of int is also 64 bits. Terrible solution. AC Op-amp integrator with DC Gain Control in LTspice. "-D_FILE_OFFSET_BITS=64" "-Wall" "-Winvalid-pch" "-g" "-Wthread-safety" "-Wno-microsoft-enum-forward-reference" "-Wno-unused-function" "-Wno-sometimes-unini The point is (probably) that the value passed to the thread is an integer value, not really a 'void *'. But this code pass the normal variable .. Mutually exclusive execution using std::atomic? For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. The following program casts a double to an int. you can just change architecture to support 32 bit compilation by all below in in Build Settings. I don't see how anything bad can happen . 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; Floating-point conversions Linear regulator thermal information missing in datasheet. Maybe you can try this too. The problem is not with casting, but with the target type loosing half of the pointer. Using printf with a pointer to float gives an error, Meaning of int (*) (int *) = 5 (or any integer value), Casting int to void* loses precision, and what is the solution in required cases, Acidity of alcohols and basicity of amines. If this is the data to a thread procedure, then you quite commonly want to pass by value. The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS, AC Op-amp integrator with DC Gain Control in LTspice, Identify those arcade games from a 1983 Brazilian music video. 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. C99 defines the types "intptr_t" and "uintptr_t" which do . GitHub. The subreddit for the C programming language, Press J to jump to the feed. Remarks. This is what the second warning is telling you. It's always a good practice to put your #define's in brackets to avoid such surprise. How to use Slater Type Orbitals as a basis functions in matrix method correctly? *sound/soc/codecs/tlv320aic32x4.c:1202:18: warning: cast to smaller integer type 'enum aic32x4_type' from 'void *' @ 2022-04-22 9:48 kernel test robot 0 siblings, 0 . Can Martian regolith be easily melted with microwaves? Now, what happens when I run it with the thread sanitizer? This is not a conversion at all. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. Actions. ncdu: What's going on with this second size column? There's no proper way to cast this to int in general case. 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. What is the purpose of this D-shaped ring at the base of the tongue on my hiking boots? On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. A cast specifies a conversion from one type to another. Why does flowing off the end of a non-void function without returning a value not produce a compiler error? SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. Have a question about this project? But I'm nitpicking .. How do I work around the GCC "error: cast from SourceLocation* to int loses precision" error when compiling cmockery.c? Hence there is no loss in data. 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. The difference between the phonemes /p/ and /b/ in Japanese. 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. "After the incident", I started to be more careful not to trip over things. Since gcc compiles that you are performing arithmetic between void* and an int (1024). this way you won't get any warning. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? How do I force make/GCC to show me the commands? whether it was an actual problem is a different matter though. @Shahbaz you could but I will not suggest to a C newbie to use globals. @DietrichEpp can you explain what is race condition with using. Once you manage to make this cast, then what?! To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. The proper way is to cast it to another pointer type. A void pointer can be really useful if the programmer is not sure about the data type of data inputted by the end user. Replacing broken pins/legs on a DIP IC package, AC Op-amp integrator with DC Gain Control in LTspice. So make sure you understand what you are doing! Connect and share knowledge within a single location that is structured and easy to search. @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. Your first example is risky because you have to be very careful about the object lifetimes. Replacing broken pins/legs on a DIP IC package, How to handle a hobby that makes income in US. SCAN_PUT(ATTR, NULL); How to tell which packages are held back due to phased updates, Identify those arcade games from a 1983 Brazilian music video. If you call your thread creation function like this, then the void* arriving inside of myFcn has the value of the int you put into it. How Intuit democratizes AI development across teams through reusability. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? If you preorder a special airline meal (e.g. Thanks for contributing an answer to Stack Overflow! Does ZnSO4 + H2 at high pressure reverses to Zn + H2SO4? 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 text was updated successfully, but these errors were encountered: It is commonly called a pointer to T and its type is T*. The best way is, if one can, do not do such casting, instead, if the same memory address has to be shared for pointer and int (e.g. } SCAN_END_SINGLE(ATTR) By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. A pointer converted to an integer of sufficient size and back to the same pointer type is guaranteed to have its original value, otherwise the resulting pointer cannot be dereferenced safely ( the round-trip conversion in the opposite direction is not guaranteed [.]) with ids being an array of ints and touch being a pointer. Star 675. 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). The result is the same as implicit conversion from the enum's underlying type to the destination 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 the function had the correct signature you would not need to cast it explicitly. Type casting is when you assign a value of one primitive data type to another type. static_cast on the other hand should deny your stripping away the const qualifier. I assumed that gcc makes a 65536 out of my define, but I was wrong. Can I tell police to wait and call a lawyer when served with a search warrant? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. So,solution #3 works just fine. 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. "clang" "-Ilib\libopenvswitch.a.p" "-Ilib" "-I..\lib" "-I." Evaluate integer expressions in a larger size before comparing or assigning to that size.Note that (time_+t)-1 also complies with INT31-C-EX3. Making statements based on opinion; back them up with references or personal experience. In the first example, the variable c1 of the char type is converted to a temporary variable of the int type, because the second operand in the division operation, the constant 2, is of the higher type int. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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
Find centralized, trusted content and collaborate around the technologies you use most. ), Styling contours by colour and by line thickness in QGIS. } SCAN_END_SINGLE(ATTR) Thanks for contributing an answer to Stack Overflow! If you write ((char*)ptr + 1), it will advance the pointer 1 byte, because a "char" is 1 byte. SQL Server does not automatically promote . By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. A sane compiler may throw a warning on lines like this but by no way it should throw an error, because this code is NOT wrong, it is just potentially error-prone, but can be perfectly valid. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. What I am trying to emphasis that conversion from int to pointer and back again can be frough with problems as you move from platform to platform. 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. returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size);
So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. Disconnect between goals and daily tasksIs it me, or the industry? */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
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cast to void *' from smaller integer type 'int
