cast to void *' from smaller integer type 'int
Not the answer you're looking for? And, most of these will not even work on gcc4. 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). (i.e. use $(ARCHS_STANDARD_32_BIT) at Architecture instead of $(ARCHS_STANDARD). However, I believe that even if the define was for the "65536", it would not be what @kaetzacoatl wanted. Find centralized, trusted content and collaborate around the technologies you use most. An object pointer (including void*) or function pointer can be converted to an integer type using reinterpret_cast. Taking the above declarations of A, D, ch of the . So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. In Java, there are two types of casting: Widening Casting (automatically) - converting a smaller type to a larger type size. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? 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. The difference between a and &a is the type. The correct answer is, if one does not mind losing data precision. @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. If you convert (void*) to (long) no precision is lost, then by assigning the (long) to an (int), it properly truncates the number to fit. error: comparison between pointer and integer ('int' and 'string' (aka 'char *')), CS50 Caesar program is working but check50 says it isn't. You can use a 64 bits integer instead howerver I usually use a function with the right prototype and I cast the function type : Identify those arcade games from a 1983 Brazilian music video. - the incident has nothing to do with me; can I use this this way? And in this context, it is very very very common to see programmers lazily type cast the. I assumed that gcc makes a 65536 out of my define, but I was wrong. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Setting a buffer of char* with intermediate casting to int*. A nit: in your version, the cast to void * is unnecessary. Find centralized, trusted content and collaborate around the technologies you use most. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. I'm trying to create a void* from an int. Making statements based on opinion; back them up with references or personal experience. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. */ >> -bool >> +enum conversion_safety >> unsafe_conversion_p (tree type, tree expr, bool . property that any valid pointer to void can be converted to this type, Converting a pointer to an integer whose result cannot represented in the integer type is undefined behavior is C and prohibited in C++. RNINGS" "-D_CRT_SECURE_NO_DEPRECATE" -MD -MQ lib/libopenvswitch.a.p/odp-util.c.obj -MF "lib\libopenvswitch.a.p\odp-util.c.obj.d" -o lib/libopenvswitch.a.p/od Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? 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. I cannot reverse my upvote of user384706's answer, but it's wrong. Can Martian regolith be easily melted with microwaves? You can use any other pointer, or you can use (size_t), which is 64 bits. The cast back to int * is not, though. SCAN_PUT_ATTR(key, ATTR, skey, FUNC); Even though what you say regarding the lifetime of the object is true, integral types are too limited for a generic API. Implicit Type Conversion is also known as 'automatic type conversion'. You can fix this error by replacing this line of code. Find centralized, trusted content and collaborate around the technologies you use most. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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. I think the solution 3> should be the correct one. p-util.c.obj "-c" ../lib/odp-util.c If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. windows meson: cast to smaller integer type 'unsigned long' from 'void *'. How to tell which packages are held back due to phased updates, Identify those arcade games from a 1983 Brazilian music video. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. The value of float variable is= 37.75. Anw, the project still build and run normally when i use Xcode 5.0 with iOS 7.0. In such a case the programmer can use a void pointer to point to the location of the unknown data type. 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. My code is all over the place now but I appreciate you all helping me on my journey to mastery! How to convert a factor to integer\numeric without loss of information? And then assign it to the double variable. 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. C/C++ , Cerror: cast to 'void *' from smaller integer type 'int'. Why did Ukraine abstain from the UNHRC vote on China? Not the answer you're looking for? Disconnect between goals and daily tasksIs it me, or the industry? 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. The following program casts a double to an int. reinterpret_cast is a type of casting operator used in C++. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? 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. To avoid truncating your pointer, cast it to a type of identical size. Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. That's not a good idea if the original object (that was cast to void*) was an integer. The problem was there before, you just are being notified of it. 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. If you do this, you have the thread reference a value that (hopefully still) lives in some other thread. 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 Connect and share knowledge within a single location that is structured and easy to search. 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. BUT converting a pointer to void* and back again is well supported (everywhere). But assuming that it is, as long as the caller and the callee agree, you can do that sort of thing. Such pointers can be stored in 32-bit data types (for instance, int, DWORD). I would create a structure and pass that as void* to pthread_create. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? Maybe you can try this too. 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. @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' Once you manage to make this cast, then what?! It is done by the compiler on its own, without any external trigger from the user. ncdu: What's going on with this second size column? // 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. 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 is the point of Thrower's Bandolier? Why is this sentence from The Great Gatsby grammatical? Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. I'm trying to learn pthreads and thing that keeps bugging me is how do i really pass argument to the function. 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. */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; This is not even remotely "the correct answer". Don't pass your int as a void*, pass a int* to your int, so you can cast the void* to an int* and copy the dereferenced pointer to your int. @DavidHeffernan, sane thread APIs wouldn't send integral data to the thread procedures, they would send pointers. To cast such pointers to 32-bit types and vice versa special functions are used: void * Handle64ToHandle ( const void * POINTER_64 h ) void * POINTER_64 HandleToHandle64 ( const void *h ) long HandleToLong ( const void *h ) unsigned long HandleToUlong ( const void *h ) Functions return bigint only if the parameter expression is a bigint data type. Your first example is risky because you have to be very careful about the object lifetimes. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. However even though their types are different, the address is going to be the same. A missing cast in the new fast > enumeration code. Error while setting app icon and launch image in xcode 5.1. Making statements based on opinion; back them up with references or personal experience. The proper way is to cast it to another pointer type. For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. 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; rev2023.3.3.43278. This page was last modified on 12 February 2023, at 18:25. If you cast an int pointer int, you might get back a different integer. And in the function you get the value of the pointer by using the dereference operator *: Please read why glib provide macros for this kind of conversions, there's no need to repeat the text here. If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . This forum has migrated to Microsoft Q&A. The point is (probably) that the value passed to the thread is an integer value, not really a 'void *'. Apparently the clang version in Xcode 5.1 and above is more strict about potential 32bit vs. 64 bit incompatibilities in source code than older clang versions have been. 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. I'm using cocos2d-x-2.2.2. The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' Pd = Pa; Similarly, Pc may be type cast to type int and assigned the value Pa. 1. How to use Slater Type Orbitals as a basis functions in matrix method correctly? @LearnCocos2D: so, how can i "overcome" the error without editing any not-my-code or in-library-file lines? This is what the second warning is telling you. It generally takes place when in an expression more than one data type is present. That's probably going to be true for most platforms you will ever encounter, but it's not a guarantee; it's implementation-dependent. What is the purpose of non-series Shimano components? Does Counterspell prevent from any further spells being cast on a given turn? How to notate a grace note at the start of a bar with lilypond? There's no proper way to cast this to int in general case. what happens when we typecast normal variable to void* or any pointer variable? Connect and share knowledge within a single location that is structured and easy to search. (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. How Intuit democratizes AI development across teams through reusability. Is it possible to create a concave light? The subreddit for the C programming language, Press J to jump to the feed. Yeah, the tutorial is doing it wrong. Why is this sentence from The Great Gatsby grammatical? Does a summoned creature play immediately after being summoned by a ready action? @Martin York: No, it doesn't depend on endiannness. 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;. STR34-C. This page has been accessed 1,655,678 times. SQL Server does not automatically promote . ../lib/odp-util.c:5489:33: note: expanded from macro 'SCAN_PUT_ATTR' Just edited. But the problem has still happened. Remarks. Acidity of alcohols and basicity of amines. 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. Just want to point out that the purpose of threads is, +1 absolutely true, but if you take you time to write struct {}, you can save a lot of troubles in the future when you want to receive/send more data then just an int. Since all pointers on 64-bit Windows are 64 bits, you are growing the data size from 32 bits backto 64 bits. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @Dinesh: could you please 1) show us those. 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. Yeah, the tutorial is doing it wrong. On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. If your code has the chance to ever be ported to some platform where this doesn't hold, this won't work. Basically its a better version of (void *)i. Are there tables of wastage rates for different fruit and veg? Not the answer you're looking for? 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. But gcc always give me a warning, that i cannot cast an int to a void*. static const void* M_OFFSET = (void*)64*1024; Since gcc compiles that you are performing arithmetic between void* and an int ( 1024 ). rev2023.3.3.43278. How do I check if a string represents a number (float or int)? Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? If your standard library (even if it is not C99) happens to provide these types - use them. casting from int to void* and back to int. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul It solved my problem too. 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. Windows has 32 bit long only on 64 bit as well. Passing arguments to pthread_create - invalid conversion from void(*)() to void(*)(void*). Does melting sea ices rises global sea level? Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, "what happen when typcating normal variable to void* or any pointer variable?" Converting a void* to an int is non-portable way that may work or may not! The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. Safe downcast may be done with dynamic_cast. Thanks for contributing an answer to Stack Overflow! "clang" "-Ilib\libopenvswitch.a.p" "-Ilib" "-I..\lib" "-I." You can convert the values from one type to another explicitly using the cast operator as follows (type_name) expression [] 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). (void *)i Error: cast to 'void *' from smaller integer type 'int' PS: UBUNTUCLANG3.5 clang -O0 -std=gnu11 -march=native -lm -lpthread pagerank.c -o pagerank c pthreads 4 10.3k 2 21 2015-06-05 Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. Can I tell police to wait and call a lawyer when served with a search warrant? Asking for help, clarification, or responding to other answers. Don't do that. ), For those who are interested. 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. Issues. "-D_FILE_OFFSET_BITS=64" "-Wall" "-Winvalid-pch" "-g" "-Wthread-safety" "-Wno-microsoft-enum-forward-reference" "-Wno-unused-function" "-Wno-sometimes-unini All float types are to be converted to double. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. That could create all kinds of trouble. Asking for help, clarification, or responding to other answers. Any expression can be cast to type void (which means that the result of the expression is ignored), but it's not legal to cast an expression of type void to type int not least because the result of such a cast wouldn't make any sense. You are correct, but cocos actually only uses that address as a unique id. Thanks for contributing an answer to Stack Overflow! By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. If your standard library (even if it is not C99) happens to provide these types - use them. void* -> integer -> void* rather than integer -> void* -> integer. I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. 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. Otherwise, if the original pointer value points to an object a, and there is an object b of the . Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? You cannot just cast the 32-bit variable to a pointer, because that pointer on a 64-bit machine is twice as long. 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. Bulk update symbol size units from mm to map units in rule-based symbology.
