You can only do this if you use a synchronization primitive to ensure that there is no race condition. Thanks for contributing an answer to Stack Overflow! Thus as a result it may be less error prone to generate a pointer dynamcially and use that. rev2023.3.3.43278. itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? You need to pass an actual pointer. 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. iphone - Error "Cast from pointer to smaller type 'int' loses Java Type Casting. what does it mean to convert int to void* or vice versa? 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. A nit: in your version, the cast to void * is unnecessary. 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. Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. 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. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. even though the compiler doesn't know you only ever pass myFcn to pthread_create in conjunction with an integer. Since all pointers on 64-bit Windows are 64 bits, you are growing the data size from 32 bits backto 64 bits. How do I work around the GCC "error: cast from SourceLocation* to int loses precision" error when compiling cmockery.c? I think the solution 3> should be the correct one. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ So,solution #3 works just fine. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? Typecasting - Data Types - Language Basics - MQL4 Reference Actions. 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. Create an account to follow your favorite communities and start taking part in conversations. } SCAN_END_SINGLE(ATTR) This is why you got Error 1 C2036, from your post. What does it mean to convert int to void* or vice versa? Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). Converting a pointer to an integer whose result cannot represented in the integer type is undefined behavior is C and prohibited in C++. The point is (probably) that the value passed to the thread is an integer value, not really a 'void *'. Your first example is risky because you have to be very careful about the object lifetimes. SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); Clang warnings for an invalid casting? - The FreeBSD Forums ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] 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. I recall there was a TreeNode(int) early on prior to 1.0 release I can't remember why I removed it, if I should felt it was easy enough to cast to (void*) or if it was because it created type inference conflict at the call site. You should perform type conversion based on 64bit build system because the type "int" supports only -32768 ~ 32768. 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. How to correctly type cast (void*)? - social.msdn.microsoft.com 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. Not the answer you're looking for? a is of type int[4], which can be implicitly cast to int* (ie, a pointer to an int) &a is of type int(*)[4] (ie: a pointer to an array of 4 ints). And then assign it to the double variable. [Solved] Properly casting a `void*` to an integer in C++ Hence there is no loss in data. The difference between the phonemes /p/ and /b/ in Japanese. Wrong. Such pointers can be stored in 32-bit data types (for instance, int, DWORD). Using an integer address (like &x) is probably wrong, indeed each modification you will execute on x will affect the pass behaviour. Why do small African island nations perform better than African continental nations, considering democracy and human development? ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' B programing language is a language based on basic combined programming or a BCPL, and it is the precursor of the C programming language. Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. } SCAN_END_SINGLE(ATTR) Does melting sea ices rises global sea level? However, you are also casting the result of this operation to (void*). Infact I know several systems where that does not hold. How can this new ban on drag possibly be considered constitutional? An open (void) pointer can hold a pointer of any type. Connect and share knowledge within a single location that is structured and easy to search. @BlueMoon Thanks a lot! reinterpret_cast<void *>(42)). ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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. Thanks Jonathan, I was thinking about my answer in another thread: AraK is correct, passing integers a pointers are not necessarily interchangeable. Cast Operations - Oracle Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Xcode 5 and iOS 7: Architecture and Valid architectures, xcode build error: Semantic issue cast from pointer to smaller type 'int' loses information, Issues in handling touches on subviews(uiviews) in UIScrollView, Architecture linking error after Xcode 5.1 upgrade, iOS 7.1 gives error after updating to Xcode 5.1, Linker error in Xcode 5.1 with cocos2d-x 3 beta 2. This allows you to reinterpret the void * as an int. STR34-C. Note that it's not guaranteed that casting an, Generally this kind of type casting does not lead to any concern as long as the addresses are encoded using the same length as the "variable type" (. Half your pointer will be garbage. "-D_FILE_OFFSET_BITS=64" "-Wall" "-Winvalid-pch" "-g" "-Wthread-safety" "-Wno-microsoft-enum-forward-reference" "-Wno-unused-function" "-Wno-sometimes-unini static_cast conversion - cppreference.com with ids being an array of ints and touch being a pointer. Therefore it is perfectly valid for the compiler to throw an error for a line like. However the actual code in question contains an explicit c-style cast to int. 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. 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. Bulk update symbol size units from mm to map units in rule-based symbology. Passing arguments to pthread_create - invalid conversion from void(*)() to void(*)(void*). 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 are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? AC Op-amp integrator with DC Gain Control in LTspice. The difference between a and &a is the type. int, bigint, smallint, and tinyint (Transact-SQL) - SQL Server Offline ImPer Westermark over 11 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. In simple example code like this it's very easy to convince yourself that there's no problem, but in more elaborate real-world scenarios it's very easy to make this mistake inadvertently. How Intuit democratizes AI development across teams through reusability. clang11 report error: cast to smaller integer type #82 - GitHub whether it was an actual problem is a different matter though. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Setting a buffer of char* with intermediate casting to int*. Then i can continue compiling. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' How do I align things in the following tabular environment? 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. No sense in writing a few dozen lines of extra code just to get a bunch of numbered threads. . linux c-pthreads: problem with local variables. Already on GitHub? 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 [.]) The problem was there before, you just are being notified of it. Remarks. Identify those arcade games from a 1983 Brazilian music video. ^~~~~~~~~~~~~~~~~~~~~ - the incident has nothing to do with me; can I use this this way? Casting type void to uint8_t - Arduino Forum 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; Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. If you need to keep the returned address, just keep it as void*. In Java, there are two types of casting: Widening Casting (automatically) - converting a smaller type to a larger type size. 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. Even though what you say regarding the lifetime of the object is true, integral types are too limited for a generic API. casting from int to void* and back to int - C / C++ Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? Recovering from a blunder I made while emailing a professor. A nit: in your version, the cast to void * is unnecessary. In such a case the programmer can use a void pointer to point to the location of the unknown data type. Can I tell police to wait and call a lawyer when served with a search warrant? Thanks for contributing an answer to Stack Overflow! Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? In this case, casting the pointer back to an integer is meaningless, because . arrays - I get the error: "cast to smaller integer type 'int' from Where does this (supposedly) Gibson quote come from? Linear regulator thermal information missing in datasheet. Thanks for contributing an answer to Stack Overflow! He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. If the function had the correct signature you would not need to cast it explicitly. cast to 'void *' from smaller integer type 'int' Implicit Type Conversion in C with Examples - GeeksforGeeks [] ExplanatioUnlike static_cast, but like const_cast, the reinterpret_cast expression does not compile to any CPU instructions (except when converting between integers and pointers or on obscure architectures where pointer representation depends on its type). If this is the data to a thread procedure, then you quite commonly want to pass by value. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. I need to convert the argument to an int for later use: The compiler (GCC version 4.2.4) returns the error: You can cast it to an intptr_t type. Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. How to use Slater Type Orbitals as a basis functions in matrix method correctly? This page has been accessed 1,655,678 times. For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. unsigned long call_fn = (unsigned long)FUNC; If the value is ever used as pointer again that will prove to be an extremely bad idea. ^~~~~~~~~~~~~~~~~~~~~ From the question I presume the OP does. Replacing broken pins/legs on a DIP IC package, How to handle a hobby that makes income in US. The OP wanted to convert a pointer value to a int value, instead, most the answers, one way or the other, tried to wrongly convert the content of arg points to to a int value. As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). 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. 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. @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. c - type casting integer to void* - Stack Overflow The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. 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. how to cascade 2d int array to 2d void pointer array? ^~~~~~~~~~~~~~~~~~~ Making statements based on opinion; back them up with references or personal experience. This is an old C callback mechanism so you can't change that. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. what does it mean to convert int to void* or vice versa? Not the answer you're looking for? To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. Then I build my project, I get the error "Cast from pointer to smaller type 'int' loses information" in EAGLView.mm file (line 408) when 64-bit simulators (e.g. Any help with this is appreciated. What I am saying is that it would be safer to use new(5) rather than 5 and deal with it appropriately at the other end. SQL Server does not automatically promote . Issues. I assumed that gcc makes a 65536 out of my define, but I was wrong. This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. 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). ERROR: incompatible integer to pointer conversion assigning to 'string' (aka 'char *') from 'int', error: cast to 'string' (aka 'char *') from smaller integer type 'int' [-Werror,-Wint-to-pointer-cast], error: incompatible integer to pointer conversion assigning to 'string' (aka 'char *') from 'int' C, warning: initialization of 'unsigned char' from 'uint8_t *' {aka 'unsigned char *'} makes integer from pointer without a cast [-Wint-conversion], Minimising the environmental effects of my dyson brain. In such condition type conversion (type promotion) takes place to avoid loss of data. This is flat out wrong. windows meson: cast to smaller integer type 'unsigned long' from 'void *'. I cannot reverse my upvote of user384706's answer, but it's wrong. @Martin York: No, it doesn't depend on endiannness. The preprocessor will replace your code by this: This is unlikely what you are trying to do. How do I set, clear, and toggle a single bit? Visit Microsoft Q&A to post new questions. 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. This solution is in accordance with INT18-C. If you really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. My code is all over the place now but I appreciate you all helping me on my journey to mastery! Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? Casting a pointer to void* and back is valid use of reinterpret_cast<>. ^~~~~~~~~~~~~~~~~~~~ This is not a conversion at all. On all of them int is 32bit, not 16bit. Type Casting in C Language with Examples - Dot Net Tutorials Mutually exclusive execution using std::atomic? Casting Pointers - IBM Typically, long or unsigned long is . The main point is: a pointer has a platform dependent size. 471,961 Members | 900 Online. property that any valid pointer to void can be converted to this type, Star 675. Why is there a voltage on my HDMI and coaxial cables? C++ Tutorial => Conversion between pointer and integer For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. 4. Type Conversions - C in a Nutshell [Book] - O'Reilly Online Learning What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? Is a PhD visitor considered as a visiting scholar. p-util.c.obj "-c" ../lib/odp-util.c for (i=0, j=0; j
