cast to void *' from smaller integer type 'int

GitHub Skip to content Product Solutions Open Source Pricing Sign in Sign up smadaminov / ovs-dpdk-meson-issues Public Notifications Fork 1 Star 1 Code Issues 66 Pull requests Actions Projects 1 Security Insights New issue The problem is not with casting, but with the target type loosing half of the pointer. Remembering to delete the pointer after use so that we don't leak. Connect and share knowledge within a single location that is structured and easy to search. 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. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. This forum has migrated to Microsoft Q&A. Passing arguments to pthread_create - invalid conversion from void(*)() to void(*)(void*). 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 ) Get the address of a callback function to call dynamically in C++, error: call of overloaded function ambiguous, error: cast from to unsigned int loses precision [-fpermissive]. The problem just occur with Xcode 5.1. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? 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. So,solution #3 works just fine. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. But you seem to suggest by your answer that the user can pass 5 to pthread_create and then perform the above cast to get it back. Find centralized, trusted content and collaborate around the technologies you use most. In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. 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; The value of float variable is= 37.75. B language was designed to develop . Terrible solution. Replacing broken pins/legs on a DIP IC package, AC Op-amp integrator with DC Gain Control in LTspice. and how to print the thread id of 2d array argument? Notifications. Typically, long or unsigned long is . The only alternative is really to take time and fix all 64-bit code issues, of which there may be some non-trivial issues. You are correct, but cocos actually only uses that address as a unique id. In the first example, the variable c1 of the char type is converted to a temporary variable of the int type, because the second operand in the division operation, the constant 2, is of the higher type int. void* -> integer -> void* rather than integer -> void* -> integer. But gcc always give me a warning, that i cannot cast an int to a void*. 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 The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. 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 converted back to pointer to void, and the result will compare equal Or, they are all wrong. Linear regulator thermal information missing in datasheet. This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. *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 . By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. "After the incident", I started to be more careful not to trip over things. that any valid pointer to void can be converted to this type, then If you are going to pass the address you typically need to exert some more control over the lifetime of the object. How can this new ban on drag possibly be considered constitutional? Well occasionally send you account related emails. But, sure, in that specific case you can pass a local variable address, type casting integer to void* [duplicate]. But assuming that it is, as long as the caller and the callee agree, you can do that sort of thing. Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. property that any valid pointer to void can be converted to this type, You cannot just cast the 32-bit variable to a pointer, because that pointer on a 64-bit machine is twice as long. actually no, as int my be a smaller type than a pointer ;-) But, of course with int64_t it works fine. This will only compile if the destination type is long enough. 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. The subreddit for the C programming language, Press J to jump to the feed. Update: Today, i download the latest version of cocos2d-x (cocos2d-x 2.2.3). B programing language is a language based on basic combined programming or a BCPL, and it is the precursor of the C programming language. 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. return ((void **) returnPtr);} /* Matrix() */. He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. You can only do this if you use a synchronization primitive to ensure that there is no race condition. pthread passes the argument as a void*. 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; 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). 471,961 Members | 900 Online. *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 . ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] If the function had the correct signature you would not need to cast it explicitly. 10) A prvalue of type pointer to void (possibly cv-qualified) can be converted to pointer to any object type. GitHub. Thanks. 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. Can I tell police to wait and call a lawyer when served with a search warrant? Just re-enforcing the old behavior of Xcode 5.0 and earlier versions, that already cut away parts of the address by casting it to int, won't introduce any new bugs and avoids the need to learn and understand lots of implementation-internal cocos code. Usually that means the pointer is allocated with. Why is there a voltage on my HDMI and coaxial cables? Converting a pointer to an integer whose result cannot represented in the integer type is undefined behavior is C and prohibited in C++. 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. I need to cast the int from the first function so that I can use it as an argument for the second function. I cannot reverse my upvote of user384706's answer, but it's wrong. By clicking Sign up for GitHub, you agree to our terms of service and Only the following conversions can be done with static_cast, except when such conversions would cast away constness or volatility. to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. In such condition type conversion (type promotion) takes place to avoid loss of data. 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. Thanks for contributing an answer to Stack Overflow! 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. Find centralized, trusted content and collaborate around the technologies you use most. How Intuit democratizes AI development across teams through reusability. What video game is Charlie playing in Poker Face S01E07? Whats the grammar of "For those whose stories they are"? Is it suspicious or odd to stand by the gate of a GA airport watching the planes? Type casting is when you assign a value of one primitive data type to another type. For integer casts in specific, using into() signals that . 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" (. Asking for help, clarification, or responding to other answers. long guarantees a pointer size on Linux on any machine. What does it mean to convert int to void* or vice versa? Why did Ukraine abstain from the UNHRC vote on China? Windows has 32 bit long only on 64 bit as well. On most platforms pointers and longs are the same size, but ints and pointers often are not the same size on 64bit platforms. Why does Mister Mxyzptlk need to have a weakness in the comics? But I don't want to edit code in "EAGLView.mm" because it's a "library file". Please tell me error: cast from 'void*' to 'int' loses precision, How Intuit democratizes AI development across teams through reusability. The main point is: a pointer has a platform dependent size. How to use Slater Type Orbitals as a basis functions in matrix method correctly? It generally takes place when in an expression more than one data type is present. So you know you can cast it back like this. byte -> short -> char -> int -> long -> float -> double. 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. You can convert the values from one type to another explicitly using the cast operator as follows (type_name) expression Sign up for a free GitHub account to open an issue and contact its maintainers and the community. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. How to notate a grace note at the start of a bar with lilypond? Thanks for contributing an answer to Stack Overflow! Find centralized, trusted content and collaborate around the technologies you use most. And in this context, it is very very very common to see programmers lazily type cast the. what does it mean to convert int to void* or vice versa? Are there tables of wastage rates for different fruit and veg? XCode 5.1 is change all architecture to 64 bit. 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. @Martin York: No, it doesn't depend on endiannness. What is the difference between const int*, const int * const, and int const *? Implementation-dependent. If the destination type is bool, this is a boolean conversion (see below). A long long would not work for 32bit systems and a long would not work for 64 bit Windows (while 64bit Unix and Unix-like systems like OS X use the LP64 data model, in which a long is 64bit, 64bit Windows uses the LLP64 data model, in which a long has a size of 32bit (http://en.wikipedia.org/wiki/64-bit_computing#64-bit_data_models)). Put your define inside a bracket: without a problem. 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. SCAN_PUT(ATTR, NULL); Can I tell police to wait and call a lawyer when served with a search warrant? There's no proper way to cast this to int in general case. An object pointer (including void*) or function pointer can be converted to an integer type using reinterpret_cast. How Intuit democratizes AI development across teams through reusability. If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. BUT converting a pointer to void* and back again is well supported (everywhere). Casting a pointer to void* and back is valid use of reinterpret_cast<>. "clang" "-Ilib\libopenvswitch.a.p" "-Ilib" "-I..\lib" "-I." We have to pass address of the variable to the function because in function definition argument is pointer variable. Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] ^~~~~~~~~~~~~~~~~~~~ The correct answer is, if one does not mind losing data precision. 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. Find centralized, trusted content and collaborate around the technologies you use most. Yesterday, I updated Xcode to the newest version (5.1 (5B130a)) to compatible with iOS 7.1. reinterpret_cast is a type of casting operator used in C++. ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' There is absolutely not gurantee that sizeof(int) <= sizeof(void*). Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? ncdu: What's going on with this second size column? All character types are to be converted to an integer. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Offline ImPer Westermark over 11 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. 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. Can Martian regolith be easily melted with microwaves? Just edited. 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. p-util.c.obj "-c" ../lib/odp-util.c For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. Again, all of the answers above missed the point badly. Not the answer you're looking for? And when assigning to a void pointer, all type information is lost. I agree passing a dynamically allocated pointer is fine (and I think the best way). Projects. 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.. On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types.

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