cast to void *' from smaller integer type 'int

cast to void *' from smaller integer type 'int

Wrong. The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS. 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 Thus as a result it may be less error prone to generate a pointer dynamcially and use that. this way you won't get any warning. I cannot reverse my upvote of user384706's answer, but it's wrong. @Xax: Here's a fixed version, without the race condition: gist.github.com/depp/241d6f839b799042c409, gist.github.com/depp/3f04508a88a114734195, How Intuit democratizes AI development across teams through reusability. what does it mean to convert int to void* or vice versa? Is it possible to create a concave light? Thanks for contributing an answer to Stack Overflow! Update: Today, i download the latest version of cocos2d-x (cocos2d-x 2.2.3). What is the purpose of non-series Shimano components? How to correctly cast a pointer to int in a 64-bit application? On all of them int is 32bit, not 16bit. 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. B programing language is a language based on basic combined programming or a BCPL, and it is the precursor of the C programming language. The following behavior-changing defect reports were applied retroactively to previously published C++ standards. Converting a pointer to an integer whose result cannot represented in the integer type is undefined behavior is C and prohibited in C++. You may declare a const int variable and cast its reference to the void*. But then you need to cast your arguments inside your thread function which is quite unsafe cf. and how to print the thread id of 2d array argument? Passing arguments to pthread_create - invalid conversion from void(*)() to void(*)(void*). How can this new ban on drag possibly be considered constitutional? static const void* M_OFFSET = (void*)64*1024; Since gcc compiles that you are performing arithmetic between void* and an int ( 1024 ). 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. */ >> -bool >> +enum conversion_safety >> unsafe_conversion_p (tree type, tree expr, bool . Is it suspicious or odd to stand by the gate of a GA airport watching the planes? 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)). what happens when we typecast normal variable to void* or any pointer variable? If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . What is the difference between const int*, const int * const, and int const *? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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). The text was updated successfully, but these errors were encountered: You signed in with another tab or window. You need to pass an actual pointer. "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. vegan) just to try it, does this inconvenience the caterers and staff? To learn more, see our tips on writing great answers. Such pointers can be stored in 32-bit data types (for instance, int, DWORD). Thanks for contributing an answer to Stack Overflow! How to convert a factor to integer\numeric without loss of information? tialized" "-Wno-format" "-Wno-incompatible-pointer-types" "-Werror" "-dM" "-U_MSC_VER" "-D_TIMESPEC_DEFINED" "-D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_SECURE_NO_WA 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. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Why does setupterm terminate the program? */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); for (i=0, j=0; j returnPtr[j] = (void *) (ptr + i); // <<< Compile Errors, Error1error C2036: 'void *' : unknown sizec:\temp\testone\lib\utils.c57, 2> returnPtr[j] = (void *) ((long*)ptr + i); // <<< No compile errors, 3> returnPtr[j] = (void *) ((char*)ptr + i); // <<< No compile errors. Projects. x is a local variable and its lifetime ends as soon as control leaves the scope it was defined in. Don't do that. 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. However, you are also casting the result of this operation to (void*). For integer casts in specific, using into() signals that . 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:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] rev2023.3.3.43278. Does melting sea ices rises global sea level? should we also have a diagnostic for the (presumed) user error? even though the compiler doesn't know you only ever pass myFcn to pthread_create in conjunction with an integer. Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. If any, how can the original function works without errors if we just ignore the warning. Type casting is when you assign a value of one primitive data type to another type. This will only compile if the destination type is long enough. Narrowing Casting (manually) - converting a larger type to a . Returns a value of type new-type. He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. Please note that the error I am receiving is "cast to smaller integer type 'int' from 'string' (aka 'char *')" referencing line of code: while (isalpha(residents[i].name) == 0). Visit Microsoft Q&A to post new questions. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). 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. 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. 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. Using an integer address (like &x) is probably wrong, indeed each modification you will execute on x will affect the pass behaviour. Find centralized, trusted content and collaborate around the technologies you use most. Replacing broken pins/legs on a DIP IC package, AC Op-amp integrator with DC Gain Control in LTspice. The point is (probably) that the value passed to the thread is an integer value, not really a 'void *'. I have a function with prototype void* myFcn(void* arg) which is used as the starting point for a pthread. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? 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 ) Using Kolmogorov complexity to measure difficulty of problems? Anw, the project still build and run normally when i use Xcode 5.0 with iOS 7.0. Connect and share knowledge within a single location that is structured and easy to search. property that any valid pointer to void can be converted to this type, The preprocessor will replace your code by this: This is unlikely what you are trying to do. 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. ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' static_cast on the other hand should deny your stripping away the const qualifier. It's an int type guaranteed to be big enough to contain a pointer. A missing cast in the new fast > enumeration code. It generally takes place when in an expression more than one data type is present. It solved my problem too. 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. 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. ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] If you are going to pass the address you typically need to exert some more control over the lifetime of the object. Sign in 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. lexborisov Modest Public. Yesterday, I updated Xcode to the newest version (5.1 (5B130a)) to compatible with iOS 7.1. I'm trying to learn pthreads and thing that keeps bugging me is how do i really pass argument to the function. If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. 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 [.]) What is the purpose of this D-shaped ring at the base of the tongue on my hiking boots? 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. Implicit Type Conversion is also known as 'automatic type conversion'. ../lib/odp-util.c:5601:9: note: expanded from macro 'SCAN_PUT' You just need to suppress the warning, and this will do it: This may offend your sensibilities, but it's very short and has no race conditions (as you'd have if you used &i). 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. How do I check if a string represents a number (float or int)? "-I.." "-Iinclude\openflow" "-I..\include\openflow" "-Iinclude\openvswitch" "-I..\include\openvsw I'm trying to create a void* from an int. actually no, as int my be a smaller type than a pointer ;-) But, of course with int64_t it works fine. 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. "After the incident", I started to be more careful not to trip over things. A cast converts an object or value from one type to another. casting from int to void* and back to int. The subreddit for the C programming language, Press J to jump to the feed. Please help me compile Chez Scheme. You could use this code, and it would do the same thing as casting ptr to (char*). LLNL's tutorial is bad and they should feel bad. As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). SCAN_PUT(ATTR, NULL); I wish that you write those answer first than the explanation. In the best case this will give the same results as the original code, with no advantages, but in the worst case it will fail in multiple catastrophic ways (type punning, endianness, less efficient, etc. Mutually exclusive execution using std::atomic? equal to the original pointer: First you are using a define, which is not a variable. converted back to pointer to void, and the result will compare equal You are getting warnings due to casting a void* to a type of a different size. In C (int)b is called an explicit conversion, i.e. I would create a structure and pass that as void* to pthread_create. It is done by the compiler on its own, without any external trigger from the user. You are right! What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? 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. The int data type is the primary integer data type in SQL Server. For the Nozomi from Shinagawa to Osaka, say on a Saturday afternoon, would tickets/seats typically be available - or would you need to book? I need to cast the int from the first function so that I can use it as an argument for the second function. This solution is in accordance with INT18-C. */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; Are there tables of wastage rates for different fruit and veg? Is a PhD visitor considered as a visiting scholar. Implementation-dependent. Why is there a voltage on my HDMI and coaxial cables? Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. I am an entry level C programmer. for (i=0, j=0; j. 10) A prvalue of type pointer to void (possibly cv-qualified) can be converted to pointer to any object type. C99 defines the types "intptr_t" and "uintptr_t" which do . 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. In such condition type conversion (type promotion) takes place to avoid loss of data. itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" 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; To learn more, see our tips on writing great answers. Only the following conversions can be done with static_cast, except when such conversions would cast away constness or volatility. Implementing From will result in the Into implementation but not vice-versa. SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); In Java, there are two types of casting: Widening Casting (automatically) - converting a smaller type to a larger type size. with ids being an array of ints and touch being a pointer. This is why you got Error 1 C2036, from your post. ^~~~~~~~~~~~~~~~~~~~ If you really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. 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. Connect and share knowledge within a single location that is structured and easy to search. 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. 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;. Why is this sentence from The Great Gatsby grammatical? When is casting void pointer needed in C? What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Thanks. This allows you to reinterpret the void * as an int. Bulk update symbol size units from mm to map units in rule-based symbology. Thank you all for your feedback. So you know you can cast it back like this. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? Don't do that. Where does this (supposedly) Gibson quote come from? 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. Usually that means the pointer is allocated with. Asking for help, clarification, or responding to other answers. The preprocesor absolutely will not perform arithmetic. ", "? Connect and share knowledge within a single location that is structured and easy to search. How can this new ban on drag possibly be considered constitutional? @DietrichEpp can you explain what is race condition with using. vegan) just to try it, does this inconvenience the caterers and staff? ^~~~~~~~~~~~~~~~~~~~ Asking for help, clarification, or responding to other answers. Bulk update symbol size units from mm to map units in rule-based symbology. 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. 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 your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj Mutually exclusive execution using std::atomic? XCode 5.1 is change all architecture to 64 bit. 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 most general answer is - in no way. C/C++ , Cerror: cast to 'void *' from smaller integer type 'int'. This is a fine way to pass integers to new pthreads, if that is what you need. Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. to the original pointer: The following type designates an unsigned integer type with the If your standard library (even if it is not C99) happens to provide these types - use them. (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. 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. 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! 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 Maybe you can try this too. Java Type Casting. If you preorder a special airline meal (e.g. It is commonly called a pointer to T and its type is T*. If you write ((char*)ptr + 1), it will advance the pointer 1 byte, because a "char" is 1 byte. Basically its a better version of (void *)i. 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 That could create all kinds of trouble. I am compiling this program in linux gcc compiler.. Therefore, you need to change it to long long instead of long in windows for 64 bits. Getting Command /bin/sh failed with exit code 65 Error with Xcode 5.1 . Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Setting a buffer of char* with intermediate casting to int*. Notifications. It is purely a compile-time directive which instructs the compiler to treat expression as if it had . I have looked around and can't seem to find any information on how to do this. If not, check the pointer size on your platform, define these typedefs accordingly yourself and use them. Instead of using a long cast, you should cast to size_t. Use #include to define it. If the original pointer value represents an address of a byte in memory that does not satisfy the alignment requirement of the target type, then the resulting pointer value is unspecified. If you preorder a special airline meal (e.g. Converting a void* to an int is non-portable way that may work or may not! What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? reinterpret_cast is a type of casting operator used in C++. 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. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. SCAN_PUT(ATTR, NULL); Asking for help, clarification, or responding to other answers. error: comparison between pointer and integer ('int' and 'string' (aka 'char *')), CS50 Caesar program is working but check50 says it isn't. a cast of which the programmer should be aware of what (s)he is doing. Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. In the case of Widening Type Casting, the lower data type (having smaller size) is converted into the higher data type (having larger size). Thanks for contributing an answer to Stack Overflow! Have a question about this project? The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. This is an old C callback mechanism so you can't change that. Just edited. byte -> short -> char -> int -> long -> float -> double. In a 64bit build a pointer is 64bit (contrary to a 32bit build, where it is 32bit), while an int is 32bit, so this assignment stores a 64bit value in a 32bit storage, which may result in a loss of information.

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