Java Type Casting. Not the answer you're looking for? Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. 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. To learn more, see our tips on writing great answers. 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. rev2023.3.3.43278. Once you manage to make this cast, then what?! 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. 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" (. @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. [Solved] Properly casting a `void*` to an integer in C++ (int*)Pc = pa; After the execution of the above code all the three pointers, i.e., Pa, Pd, and Pc, point to the value 150. On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" Find centralized, trusted content and collaborate around the technologies you use most. You can use a 64 bits integer instead howerver I usually use a function with the right prototype and I cast the function type : Referring to N1570 7.20.1.4/p1 (Integer types capable of holding object pointers): The following type designates a signed integer type with the property [mst-vhost:vhost 5/52] drivers/block/virtio_blk.c:539:21: warning There's no proper way to cast this to int in general case. Type Casting Of Pointers in C - Computer Notes It is purely a compile-time directive which instructs the compiler to treat expression as if it had . Thanks for contributing an answer to Stack Overflow! Taking the above declarations of A, D, ch of the . then converted back to pointer to void, and the result will compare Can I tell police to wait and call a lawyer when served with a search warrant? As Ferruccio said, int must be replaced with intptr_t to make the program meaningful. Bulk update symbol size units from mm to map units in rule-based symbology. 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. Java Type Casting (With Examples) - Programiz If you preorder a special airline meal (e.g. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. reinterpret_cast conversion - cppreference.com Connect and share knowledge within a single location that is structured and easy to search. You can also convert values from one type to another explicitly using the cast operator (see Chapter 5 ): ( type_name) expression In the following example, the cast operator causes the division of one integer variable by another to be performed as a floating-point operation: int sum = 22, count = 5; double mean = (double)sum / count; Put your define inside a bracket: without a problem. Again, all of the answers above missed the point badly. Here is some piece of code where that error occur: /cocos2d-x-2.2.2/cocos2dx/platform/ios/EAGLView.mm:408:18: Cast from pointer to smaller type 'int' loses information. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Yeah, the tutorial is doing it wrong. ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] You need to pass an actual pointer. So you could do this: Note: As sbi points out this would require a change on the OP call to create the thread. If the function had the correct signature you would not need to cast it explicitly. For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. If not, check the pointer size on your platform, define these typedefs accordingly yourself and use them. You are right! GitHub. Thus as a result it may be less error prone to generate a pointer dynamcially and use that. 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 Can Martian regolith be easily melted with microwaves? What is the point of Thrower's Bandolier? static const void* M_OFFSET = (void*)64*1024; Since gcc compiles that you are performing arithmetic between void* and an int ( 1024 ). equal to the original pointer: First you are using a define, which is not a variable. 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 ) SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); this question. 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. Bulk update symbol size units from mm to map units in rule-based symbology. Asking for help, clarification, or responding to other answers. The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function. That could create all kinds of trouble. 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. linux c-pthreads: problem with local variables. How create a simple program using threads in C? How Intuit democratizes AI development across teams through reusability. that any valid pointer to void can be converted to this type, then To subscribe to this RSS feed, copy and paste this URL into your RSS reader. whether it was an actual problem is a different matter though. I have a two functions, one that returns an int, and one that takes a const void* as an argument. C99 defines the types "intptr_t" and "uintptr_t" which do . How to use Slater Type Orbitals as a basis functions in matrix method correctly? This is memory reinterpretation - a completely unacceptable way to do what the OP is trying to do. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); Casting type void to uint8_t - Arduino Forum static_cast conversion - cppreference.com It's an int type guaranteed to be big enough to contain a pointer. Do new devs get fired if they can't solve a certain bug? -1, Uggh. Asking for help, clarification, or responding to other answers. Changing the type of ids would be the cleanest solution, but I decided against it when being confronted with this issue myself, as it only introduced a lot of issues with other code that is relying on ids being an int-array. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. 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. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? ^~~~~~~~~~~~~~~~~~~~~ FAILED: lib/libopenvswitch.a.p/odp-util.c.obj What is the purpose of this D-shaped ring at the base of the tongue on my hiking boots? ../lib/odp-util.c:5601:9: note: expanded from macro 'SCAN_PUT' What does casting to void* does when passing arguments to variadic functions? Such pointers can be stored in 32-bit data types (for instance, int, DWORD). and how to print the thread id of 2d array argument? error: cast from pointer to smaller type 'unsigned int' loses information. Making statements based on opinion; back them up with references or personal experience. Your first example is risky because you have to be very careful about the object lifetimes. Or, they are all wrong. This is why you got Error 1 C2036, from your post. You can use any other pointer, or you can use (size_t), which is 64 bits. Before I update Xcode, my project still can build and run normally with all devices. The calculated expression consists of two operations. Making statements based on opinion; back them up with references or personal experience. 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). A cast is a way of explicitly informing the compiler that you intend to make the conversion and that you are aware that data loss might occur, or the cast may fail at run time. Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul How to tell which packages are held back due to phased updates, Identify those arcade games from a 1983 Brazilian music video. return ((void **) returnPtr);} /* Matrix() */. No sense in writing a few dozen lines of extra code just to get a bunch of numbered threads. Can Martian regolith be easily melted with microwaves? If it's anything like cocos2d-iphone v2.x and just based on this slice of code in a core class I wager it's safe to say that cocos2d-x 2.x also is not compatible with 64 bit code, and you can expect all kinds of issues (not just compile-time but also runtime). If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . The compiler issues the "cast from integer to pointer of different size" warning whenever the value of an integer is converted to a pointer, especially when the memory allocated to a pointer is smaller than the memory allocated to an integer data type. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. B programing language is a language based on basic combined programming or a BCPL, and it is the precursor of the C programming language. What is the purpose of non-series Shimano components? 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. If that happens soon after the call to pthread_create() then you have a race condition, because there's a chance that the thread will attempt to read x's value after it's life has ended, which invokes undefined behavior. If your code has the chance to ever be ported to some platform where this doesn't hold, this won't work. vegan) just to try it, does this inconvenience the caterers and staff? You should perform type conversion based on 64bit build system because the type "int" supports only -32768 ~ 32768. Casting and type conversions - C# Programming Guide A cast specifies a conversion from one type to another. cast to void *' from smaller integer type 'int That's not a good idea if the original object (that was cast to void*) was an integer. 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. . However even though their types are different, the address is going to be the same. Identify those arcade games from a 1983 Brazilian music video. 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. Projects. // 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. An open (void) pointer can hold a pointer of any type. The main point is: a pointer has a platform dependent size. On most platforms pointers and longs are the same size, but ints and pointers often are not the same size on 64bit platforms. "-D_FILE_OFFSET_BITS=64" "-Wall" "-Winvalid-pch" "-g" "-Wthread-safety" "-Wno-microsoft-enum-forward-reference" "-Wno-unused-function" "-Wno-sometimes-unini 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 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. a cast of which the programmer should be aware of what (s)he is doing. Casting arguments inside the function is a lot safer. Thanks for contributing an answer to Stack Overflow! 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. This is an old C callback mechanism so you can't change that. This is flat out wrong. How to use Slater Type Orbitals as a basis functions in matrix method correctly? static_cast on the other hand should deny your stripping away the const qualifier. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? If your standard library (even if it is not C99) happens to provide these types - 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. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. You can convert the values from one type to another explicitly using the cast operator as follows (type_name) expression Please tell me error: cast from 'void*' to 'int' loses precision, How Intuit democratizes AI development across teams through reusability. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? 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 By clicking Sign up for GitHub, you agree to our terms of service and what happens when we typecast normal variable to void* or any pointer variable? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. How to correctly cast a pointer to int in a 64-bit application? To learn more, see our tips on writing great answers. How do I set, clear, and toggle a single bit? Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Star 675. you can just change architecture to support 32 bit compilation by all below in in Build Settings. From the question I presume the OP does. Pull requests. Is it possible to create a concave light? (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 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.. And, most of these will not even work on gcc4. In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Why is this sentence from The Great Gatsby grammatical? Instead of using a long cast, you should cast to size_t. Windows has 32 bit long only on 64 bit as well. Hence there is no loss in data. Click to see the query in the CodeQL repository. 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. Asking for help, clarification, or responding to other answers. Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. p-util.c.obj "-c" ../lib/odp-util.c ^~~~~~~~~~~~~~~~~~~ To be honest, I think, clang is too restrictive here. byte -> short -> char -> int -> long -> float -> double. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. The subreddit for the C programming language, Press J to jump to the feed. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? 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. What does it mean to convert int to void* or vice versa? this way I convert an int to a void* which is much better than converting a void* to an int. To learn more, see our tips on writing great answers. 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. Therefore, you need to change it to long long instead of long in windows for 64 bits. arrays - I get the error: "cast to smaller integer type 'int' from But I'm nitpicking .. "because the type "int" supports only -32768 ~ 32768" This is not true for any modern desktop or mobile OS or any OS that is targeted by cocos2d-x. 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. For integer casts in specific, using into() signals that . Are there tables of wastage rates for different fruit and veg? clang11 report error: cast to smaller integer type #82 - GitHub It solved my problem too. 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. cast to 'void *' from smaller integer type 'int' pthread create managing values generated in function (in c), Establishing TCP socket connection between PHP client and C server on Ubuntu. You think by casting it here that you are avoiding the problem! 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; Update: Today, i download the latest version of cocos2d-x (cocos2d-x 2.2.3). Floating-point conversions You are getting warnings due to casting a void* to a type of a different size. error: cast from pointer to smaller type 'unsigned int' loses Casting type int to const void* - C / C++ The text was updated successfully, but these errors were encountered: If the value is ever used as pointer again that will prove to be an extremely bad idea. @DavidHeffernan, sane thread APIs wouldn't send integral data to the thread procedures, they would send pointers. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @Dinesh: could you please 1) show us those. 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. ^~~~~~~~~~~~~~~~~~~~~ By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Most answers just try to extract 32 useless bits out of the argument. I have looked around and can't seem to find any information on how to do this. An object pointer (including void*) or function pointer can be converted to an integer type using reinterpret_cast. Since gcc compiles that you are performing arithmetic between void* and an int (1024). If you write ((char*)ptr + 1), it will advance the pointer 1 byte, because a "char" is 1 byte. 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. To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. Yesterday, I updated Xcode to the newest version (5.1 (5B130a)) to compatible with iOS 7.1. This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? If you are planning to use pthreads and you are planning to pass the pass function to pthread_create, you have to malloc/free the arguments you are planning to use (even if the threaded function just need a single int). By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Using Kolmogorov complexity to measure difficulty of problems? : iPhone Retina 4-inch 64-bit) is selected. Anw, the project still build and run normally when i use Xcode 5.0 with iOS 7.0. Cast Operations - Oracle Type Casting in C Language with Examples - Dot Net Tutorials Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. What is the difference between const int*, const int * const, and int const *? Converts between types using a combination of implicit and user-defined conversions. My code is all over the place now but I appreciate you all helping me on my journey to mastery! C++ how to get the address stored in a void pointer? Acidity of alcohols and basicity of amines. 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. Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. How can this new ban on drag possibly be considered constitutional? How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. Type conversions - cplusplus.com SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); 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 [.]) "I think what you should do is actually pass the address of the variable to the function" Not necessarily. Since all pointers on 64-bit Windows are 64 bits, you are growing the data size from 32 bits backto 64 bits. 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. 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. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. The proper way is to cast it to another pointer type. The dynamic_cast<>operator provides a way to check the actual type of a pointer to a polymorphic class. Well it does this because you are converting a 64 bits pointer to an 32 bits integer so you loose information. I am an entry level C programmer. 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. should we also have a diagnostic for the (presumed) user error? 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. LLNL's tutorial is bad and they should feel bad. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. Replacing broken pins/legs on a DIP IC package, AC Op-amp integrator with DC Gain Control in LTspice. property that any valid pointer to void can be converted to this 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.
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