I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. I am compiling this program in linux gcc compiler.. Otherwise, if the original pointer value points to an object a, and there is an object b of the . Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? @jackdoe: It's a waste of human life to write code that "you may need in the future". tialized" "-Wno-format" "-Wno-incompatible-pointer-types" "-Werror" "-dM" "-U_MSC_VER" "-D_TIMESPEC_DEFINED" "-D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_SECURE_NO_WA 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. Typically, long or unsigned long is . 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. @DietrichEpp can you explain what is race condition with using. static_cast on the other hand should deny your stripping away the const qualifier. For integer casts in specific, using into() signals that . When is casting void pointer needed in C? Fix for objc/45925 I have looked around and can't seem to find any information on how to do this. You may declare a const int variable and cast its reference to the void*. If you really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. How do I set, clear, and toggle a single bit? vegan) just to try it, does this inconvenience the caterers and staff? reinterpret_cast conversion - cppreference.com 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 . C - Type Casting - tutorialspoint.com How Intuit democratizes AI development across teams through reusability. Why does Mister Mxyzptlk need to have a weakness in the comics? ncdu: What's going on with this second size column? ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ (int) pthread_self() 64int48intuintptr_t (unsigned int) GitHub. Converting a void* to an int is non-portable way that may work or may not! Anw, the project still build and run normally when i use Xcode 5.0 with iOS 7.0. eg. Why is there a voltage on my HDMI and coaxial cables? 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.. 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). Update: Today, i download the latest version of cocos2d-x (cocos2d-x 2.2.3). Java Type Casting - W3Schools Only the following conversions can be done with static_cast, except when such conversions would cast away constness or volatility. It is purely a compile-time directive which instructs the compiler to treat expression as if it had . Again, all of the answers above missed the point badly. For example, the main thread could wait for all of the other threads to end before terminating. If this is the data to a thread procedure, then you quite commonly want to pass by value. If the destination type is bool, this is a boolean conversion (see below). (void *)i Error: cast to 'void *' from smaller integer type 'int'. Cerror: cast to 'void *' from smaller integer type 'int' 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. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. And in this context, it is very very very common to see programmers lazily type cast the. casting from int to void* and back to int - C / C++ This forum has migrated to Microsoft Q&A. Clang warnings for an invalid casting? - The FreeBSD Forums *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 . 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. B programing language is a language based on basic combined programming or a BCPL, and it is the precursor of the C programming language. @LearnCocos2D: so, how can i "overcome" the error without editing any not-my-code or in-library-file lines? But assuming that it is, as long as the caller and the callee agree, you can do that sort of thing. Re: [PATCH, PR 53001] Re: Patch to split out new warning flag for The cast back to int * is not, though. I don't see how anything bad can happen . reinterpret_cast<void *>(42)). return ((void **) returnPtr);} /* Matrix() */. So you could do this: Note: As sbi points out this would require a change on the OP call to create the thread. Basically its a better version of (void *)i. Use of Void pointers in C programming language ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] ", "!"? Yesterday, I updated Xcode to the newest version (5.1 (5B130a)) to compatible with iOS 7.1. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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; 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 Yeah, the tutorial is doing it wrong. 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. [PATCH] platform/x86: hp-wmi: Fix cast to smaller integer type warning I need to cast the int from the first function so that I can use it as an argument for the second function. Why is there a voltage on my HDMI and coaxial cables? You should perform type conversion based on 64bit build system because the type "int" supports only -32768 ~ 32768. sound/soc/codecs/tlv320aic32x4.c:1202:18: warning: cast to smaller What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? How create a simple program using threads in C? Using Kolmogorov complexity to measure difficulty of problems? 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. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' 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. 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. The difference between a and &a is the type. 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 The subreddit for the C programming language, Press J to jump to the feed. Please help me compile Chez Scheme. This is an old C callback mechanism so you can't change that. However, you are also casting the result of this operation to (void*). long guarantees a pointer size on Linux on any machine. A cast specifies a conversion from one type to another. How to correctly type cast (void*)? - social.msdn.microsoft.com How to use Slater Type Orbitals as a basis functions in matrix method correctly? Does ZnSO4 + H2 at high pressure reverses to Zn + H2SO4? LLNL's tutorial is bad and they should feel bad. In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. The text was updated successfully, but these errors were encountered: The calculated expression consists of two operations. 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. Pd = Pa; Similarly, Pc may be type cast to type int and assigned the value Pa. 1. On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. Type Casting in C Language with Examples - Dot Net Tutorials should we also have a diagnostic for the (presumed) user error? I wish that you write those answer first than the explanation. I assumed that gcc makes a 65536 out of my define, but I was wrong. This will only compile if the destination type is long enough. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. INT31-C. Ensure that integer conversions do not result in lost or Is a PhD visitor considered as a visiting scholar. Mutually exclusive execution using std::atomic? But I'm nitpicking .. Can Martian regolith be easily melted with microwaves? 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. This will get you a pointer from a 32 bit offset: A function pointer is incompatible to void* (and any other non function pointer). By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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. use $(ARCHS_STANDARD_32_BIT) at Architecture instead of $(ARCHS_STANDARD). Where does this (supposedly) Gibson quote come from? You could use this code, and it would do the same thing as casting ptr to (char*). Is it suspicious or odd to stand by the gate of a GA airport watching the planes? Have a question about this project? I get the error: "cast to smaller integer type 'int' from 'string' (aka 'char *')" referencing line of code: while (isalpha(residents[i].name) == 0), How Intuit democratizes AI development across teams through reusability. The only alternative is really to take time and fix all 64-bit code issues, of which there may be some non-trivial issues. That's probably going to be true for most platforms you will ever encounter, but it's not a guarantee; it's implementation-dependent. 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. We have to pass address of the variable to the function because in function definition argument is pointer variable. @BlueMoon Thanks a lot! Pull requests. rev2023.3.3.43278. *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 . On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. void* -> integer -> void* rather than integer -> void* -> integer. Thank you all for your feedback. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? What is the difference between const int*, const int * const, and int const *? If you preorder a special airline meal (e.g. Floating-point conversions Making statements based on opinion; back them up with references or personal experience. C++ Tutorial => Conversion between pointer and integer Your first example is risky because you have to be very careful about the object lifetimes. to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj In this case, casting the pointer back to an integer is meaningless, because . 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. How to convert a factor to integer\numeric without loss of information? How to correctly cast a pointer to int in a 64-bit application? Find centralized, trusted content and collaborate around the technologies you use most. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? SCAN_PUT_ATTR(key, ATTR, skey, FUNC); Notifications. Casting Pointers - IBM To subscribe to this RSS feed, copy and paste this URL into your RSS reader. This answer is incorrect for the reasons that have already been mentioned in the comment of, Error "Cast from pointer to smaller type 'int' loses information" in EAGLView.mm when update Xcode to 5.1 (5B130a), http://en.wikipedia.org/wiki/64-bit_computing#64-bit_data_models, http://stackoverflow.com/questions/18913906/xcode-5-and-ios-7-architecture-and-valid-architectures, How Intuit democratizes AI development across teams through reusability. XCode 5.1 is change all architecture to 64 bit. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. what does it mean to convert int to void* or vice versa? To access the object value, use the * dereference operator: int * p; assert (p == null ); p = new int (5); assert (p != null ); assert (*p == 5); (*p)++; assert (*p == 6); If a pointer contains a null value, it is not pointing to a valid object. Thanks for contributing an answer to Stack Overflow! In Java, there are two types of casting: Widening Casting (automatically) - converting a smaller type to a larger type size. SCAN_PUT(ATTR, NULL); 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. The following program casts a double to an int. Thanks for contributing an answer to Stack Overflow! From the question I presume the OP does. 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. what happens when we typecast normal variable to void* or any pointer variable? Can we typecast void into int? - Quora Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. property that any valid pointer to void can be converted to this type, Or, they are all wrong. I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . If your code has the chance to ever be ported to some platform where this doesn't hold, this won't work. It is easier to understand and write than any other assembly language. If not, check the pointer size on your platform, define these typedefs accordingly yourself and use them. 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. Does melting sea ices rises global sea level? Making statements based on opinion; back them up with references or personal experience. This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. FAILED: lib/libopenvswitch.a.p/odp-util.c.obj Remembering to delete the pointer after use so that we don't leak. The result is the same as implicit conversion from the enum's underlying type to the destination type. [Solved] Properly casting a `void*` to an integer in C++ ^~~~~~~~~~~~~~~~~~~~ byte -> short -> char -> int -> long -> float -> double. Usually that means the pointer is allocated with. Using indicator constraint with two variables. Properly casting a `void*` to an integer in C++ 24,193 Solution 1 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. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Find centralized, trusted content and collaborate around the technologies you use most. This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. Thanks for contributing an answer to Stack Overflow! Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul Implicit conversions - cppreference.com You need to cast the void* pointer to a char* pointer - and then dereference that char* pointer to give you the char that it points to! As for the stack, I've written a few libraries using pthreds, thus I don't agree that what you describe "is quite often the case". Not the answer you're looking for? Find centralized, trusted content and collaborate around the technologies you use most. Typecasting - Data Types - Language Basics - MQL4 Reference This page has been accessed 1,655,678 times. rev2023.3.3.43278. This is why you got Error 1 C2036, from your post. p-util.c.obj "-c" ../lib/odp-util.c Note:You might receive a runtime exception if the pointer contains a value unsuitable for the context. 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. To learn more, see our tips on writing great answers. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? ncdu: What's going on with this second size column? 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. Linear regulator thermal information missing in datasheet. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. To learn more, see our tips on writing great answers. For the remaining integral types, the result is the value of the enum if it can be represented by the target type and unspecified otherwise. However the actual code in question contains an explicit c-style cast to int. The preprocessor will replace your code by this: This is unlikely what you are trying to do. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Put your define inside a bracket: #define M_TABLE_SIZE (64*1024) Now, you can do: static const void* M_OFFSET = (void*) M_TABLE_SIZE; without a problem. Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. Once you manage to make this cast, then what?! The following behavior-changing defect reports were applied retroactively to previously published C++ standards. Before I update Xcode, my project still can build and run normally with all devices. Types - D Programming Language Can Martian regolith be easily melted with microwaves? Asking for help, clarification, or responding to other answers. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @Dinesh: could you please 1) show us those. As a result of the integer division 3/2 we get the value 1, which is of the int type. I'm using cocos2d-x-2.2.2. But then you need to cast your arguments inside your thread function which is quite unsafe cf. In my case, I was using a 32-bit value that needed to be passed to an OpenGL function as a void * representing an offset into a buffer. Infact I know several systems where that does not hold. He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. A void pointer can be really useful if the programmer is not sure about the data type of data inputted by the end user. I would create a structure and pass that as void* to pthread_create. This allows you to reinterpret the void * as an int. Most answers just try to extract 32 useless bits out of the argument. int, bigint, smallint, and tinyint (Transact-SQL) - SQL Server ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' It generally takes place when in an expression more than one data type is present. 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. Implicit Type Conversion is also known as 'automatic type conversion'. I'm unfamiliar with XCode, but the solution should be something like follows: Most of the "solutions" above can lose part of the pointer address when casting to a smaller type. Taking the above declarations of A, D, ch of the . Issues. error: cast from 'void*' to 'int' loses precision - Stack Overflow ^~~~~~~~~~~~~~~~~~~~~ Casting arguments inside the function is a lot safer. The problem is not with casting, but with the target type loosing half of the pointer. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ From that point on, you are dealing with 32 bits. The difference between the phonemes /p/ and /b/ in Japanese. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? But the problem has still happened. Thanks. If your standard library (even if it is not C99) happens to provide these types - use them. What is the point of Thrower's Bandolier? If your standard library (even if it is not C99) happens to provide these types - use them. Don't do that. There is no "correct" way to store a 64-bit pointer in an 32-bit integer. Does a summoned creature play immediately after being summoned by a ready action? 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. Why does setupterm terminate the program? ^~~~~~~~~~~~~~~~~~~~ An open (void) pointer can hold a pointer of any type. ../lib/odp-util.c:5601:9: note: expanded from macro 'SCAN_PUT' Yeah, the tutorial is doing it wrong. 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. ^~~~~~~~~~~~~~~~~~~ you can just change architecture to support 32 bit compilation by all below in in Build Settings. cast to 'double *' from smaller integer type 'unsigned int' The C compiler is gcc, clang version 3.9.1, target aarch64--linux-android, thread model posix. How can this new ban on drag possibly be considered constitutional? @Shahbaz you could but I will not suggest to a C newbie to use globals. If the sizes are different then endianess comes into play. Casting type void to uint8_t - Arduino Forum reinterpret_cast is a type of casting operator used in C++. The most general answer is - in no way. This is flat out wrong. Asking for help, clarification, or responding to other answers. SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); ../lib/odp-util.c:5489:33: note: expanded from macro 'SCAN_PUT_ATTR' Don't do that. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. rev2023.3.3.43278. Not the answer you're looking for? If the function had the correct signature you would not need to cast it explicitly. windows meson: cast to smaller integer type 'unsigned long' from 'void Sign up for a free GitHub account to open an issue and contact its maintainers and the community.
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