Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @Dinesh: could you please 1) show us those. casting from int to void* and back to int - C / C++ 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. You are correct, but cocos actually only uses that address as a unique id. then converted back to pointer to void, and the result will compare In such condition type conversion (type promotion) takes place to avoid loss of data. Pd = Pa; Similarly, Pc may be type cast to type int and assigned the value Pa. 1. It is purely a compile-time directive which instructs the compiler to treat expression as if it had . 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. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. How to get the error message from the error code returned by GetLastError()? 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. ../lib/odp-util.c:5489:33: note: expanded from macro 'SCAN_PUT_ATTR' casting from int to void* and back to int. Not the answer you're looking for? The main point is: a pointer has a platform dependent size. To learn more, see our tips on writing great answers. By clicking Sign up for GitHub, you agree to our terms of service and Projects. I have looked around and can't seem to find any information on how to do this. rev2023.3.3.43278. Java Type Casting. I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. vegan) just to try it, does this inconvenience the caterers and staff? 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. Wrong. Does Counterspell prevent from any further spells being cast on a given turn? eg. Using Kolmogorov complexity to measure difficulty of problems? How Intuit democratizes AI development across teams through reusability. 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! When is casting void pointer needed in C? "-I.." "-Iinclude\openflow" "-I..\include\openflow" "-Iinclude\openvswitch" "-I..\include\openvsw Well occasionally send you account related emails. 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. 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. What is the difference between const int*, const int * const, and int const *? 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. 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. 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. 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). The preprocesor absolutely will not perform arithmetic. // 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. How can this new ban on drag possibly be considered constitutional? 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). Here, the Java first converts the int type data into the double type. error: cast from pointer to smaller type 'unsigned int' loses What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. how to cascade 2d int array to 2d void pointer array? c - Cast int to void* - 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. ", "!"? Does melting sea ices rises global sea level? Error while setting app icon and launch image in xcode 5.1. 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. (void *)i Error: cast to 'void *' from smaller integer type 'int'. int, bigint, smallint, and tinyint (Transact-SQL) - SQL Server FAILED: lib/libopenvswitch.a.p/odp-util.c.obj I would create a structure and pass that as void* to pthread_create. Type conversions - cplusplus.com If the object expression refers or points to is actually a base class subobject of an object of type D, the result refers to the enclosing object of type D. Otherwise, the behavior is undefined: When the target type is bool (possibly cv-qualified), the result is false if the original value is zero and true for all other values. SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); All character types are to be converted to an integer. Actions. 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. No idea how it amassed 27 upvotes?! 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. If you do this, you have the thread reference a value that (hopefully still) lives in some other thread. What is the point of Thrower's Bandolier? How to tell which packages are held back due to phased updates, Identify those arcade games from a 1983 Brazilian music video. XCode 5.1 is change all architecture to 64 bit. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. this question. But this code pass the normal variable .. Asking for help, clarification, or responding to other answers. What you do here is undefined behavior, and undefined behavior of very practical sort. Before I update Xcode, my project still can build and run normally with all devices. I'm using cocos2d-x-2.2.2. *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 . Casting a pointer to void* and back is valid use of reinterpret_cast<>. error: cast from pointer to smaller type 'unsigned int' loses information. INT36-C. Converting a pointer to integer or integer to pointer 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. 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. It is done by the compiler on its own, without any external trigger from the user. 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. Mutually exclusive execution using std::atomic? Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? Since gcc compiles that you are performing arithmetic between void* and an int (1024). This solution is in accordance with INT18-C. Using indicator constraint with two variables. [PATCH] platform/x86: hp-wmi: Fix cast to smaller integer type warning long guarantees a pointer size on Linux on any machine. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? How to correctly cast a pointer to int in a 64-bit application? A missing cast in the new fast > enumeration code. Does a summoned creature play immediately after being summoned by a ready action? Only the following conversions can be done with static_cast, except when such conversions would cast away constness or volatility. ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' Compile error on Android ARM Issue #163 cisco/ChezScheme 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. All float types are to be converted to double. And then assign it to the double variable. I don't see how anything bad can happen . /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. Put your define inside a bracket: without a problem. Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. property that any valid pointer to void can be converted to this type, Connect and share knowledge within a single location that is structured and easy to search. 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 [.]) Making statements based on opinion; back them up with references or personal experience. Why is this sentence from The Great Gatsby grammatical? But gcc always give me a warning, that i cannot cast an int to a void*. And in this context, it is very very very common to see programmers lazily type cast the. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). Issues. STR34-C. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. A cast converts an object or value from one type to another. Is pthread_join a must when using pthread in linux? If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . rev2023.3.3.43278. Converting a void* to an int is non-portable way that may work or may not! 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. You could use this code, and it would do the same thing as casting ptr to (char*). 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 meson: cast to smaller integer type 'unsigned long' from 'void Why do academics stay as adjuncts for years rather than move around? The problem is not with casting, but with the target type loosing half of the pointer. 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. Whats the grammar of "For those whose stories they are"? Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? Implicit conversions - cppreference.com So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function. In such a case the programmer can use a void pointer to point to the location of the unknown data type. } SCAN_END_SINGLE(ATTR) How do I check if a string represents a number (float or int)? There is absolutely not gurantee that sizeof(int) <= sizeof(void*). Functions return bigint only if the parameter expression is a bigint data type. itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" Typically, long or unsigned long is . The result is the same as implicit conversion from the enum's underlying type to the destination type. If you cast an int pointer int, you might get back a different integer. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? To learn more, see our tips on writing great answers. You can only do this if you use a synchronization primitive to ensure that there is no race condition. static_cast on the other hand should deny your stripping away the const qualifier. 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. p-util.c.obj "-c" ../lib/odp-util.c