Making statements based on opinion; back them up with references or personal experience. An open (void) pointer can hold a pointer of any type. 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* -> integer -> void* rather than integer -> void* -> integer. . Cast characters to unsigned char before converting to larger integer sizes Created by Robert Seacord, last modified by Jill Britton on Oct 03, 2022 Signed character data must be converted to unsigned char before being assigned or converted to a larger signed type. How to use Slater Type Orbitals as a basis functions in matrix method correctly? On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? The problem was there before, you just are being notified of it. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. What video game is Charlie playing in Poker Face S01E07? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. p-util.c.obj "-c" ../lib/odp-util.c C99 defines the types "intptr_t" and "uintptr_t" which do . And, most of these will not even work on gcc4. Making statements based on opinion; back them up with references or personal experience. The difference between the phonemes /p/ and /b/ in Japanese. (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. int, bigint, smallint, and tinyint (Transact-SQL) - SQL Server returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size);
Type casting is when you assign a value of one primitive data type to another type. There's no proper way to cast this to int in general case. a cast of which the programmer should be aware of what (s)he is doing. ^~~~~~~~~~~~~~~~~~~~ Pull requests. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Offline ImPer Westermark over 11 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. I wish that you write those answer first than the explanation. error: comparison between pointer and integer ('int' and 'string' (aka 'char *')), CS50 Caesar program is working but check50 says it isn't. What happens if you typecast as unsigned first? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. iphone - Error "Cast from pointer to smaller type 'int' loses Why is this sentence from The Great Gatsby grammatical? Remembering to delete the pointer after use so that we don't leak. Thanks. A missing cast in the new fast > enumeration code. 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. The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS, AC Op-amp integrator with DC Gain Control in LTspice, Identify those arcade games from a 1983 Brazilian music video. ../lib/odp-util.c:5601:9: note: expanded from macro 'SCAN_PUT' If your standard library (even if it is not C99) happens to provide these types - use them. ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' 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. Taking the above declarations of A, D, ch of the . ^~~~~~~~~~~~~~~~~~~~ Bulk update symbol size units from mm to map units in rule-based symbology. ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] You should perform type conversion based on 64bit build system because the type "int" supports only -32768 ~ 32768. 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. The int data type is the primary integer data type in SQL Server. I have a two functions, one that returns an int, and one that takes a const void* as an argument. The dynamic_cast<>operator provides a way to check the actual type of a pointer to a polymorphic class. ncdu: What's going on with this second size column? Clang warnings for an invalid casting? - The FreeBSD Forums By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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. this way you won't get any warning. Using Kolmogorov complexity to measure difficulty of problems? So make sure you understand what you are doing! The text was updated successfully, but these errors were encountered: 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. 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. Since gcc compiles that you are performing arithmetic between void* and an int (1024). /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. Fork 63. 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. Java Type Casting. 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. Does a summoned creature play immediately after being summoned by a ready action? ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] - the incident has nothing to do with me; can I use this this way? SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); I think the solution 3> should be the correct one. Fix for objc/45925 you can just change architecture to support 32 bit compilation by all below in in Build Settings. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Evaluate integer expressions in a larger size before comparing or assigning to that size.Note that (time_+t)-1 also complies with INT31-C-EX3. Using indicator constraint with two variables. Getting Command /bin/sh failed with exit code 65 Error with Xcode 5.1 . Thus as a result it may be less error prone to generate a pointer dynamcially and use that.
Cast Operations - Oracle 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)). Maybe you can try this too. [Solved] Error "Cast from pointer to smaller type 'int' | 9to5Answer For example, the main thread could wait for all of the other threads to end before terminating. whether it was an actual problem is a different matter though. I'm trying to learn pthreads and thing that keeps bugging me is how do i really pass argument to the function. It is easier to understand and write than any other assembly language. 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. How can this new ban on drag possibly be considered constitutional? You use the address-of operator & to do that. vegan) just to try it, does this inconvenience the caterers and staff? ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' Basically its a better version of (void *)i. If this is the data to a thread procedure, then you quite commonly want to pass by value. On most platforms pointers and longs are the same size, but ints and pointers often are not the same size on 64bit platforms. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. Projects. How do I work around the GCC "error: cast from SourceLocation* to int loses precision" error when compiling cmockery.c? What is the purpose of non-series Shimano components? Hence there is no loss in data. What is the point of Thrower's Bandolier? "I think what you should do is actually pass the address of the variable to the function" Not necessarily. Converting a void* to an int is non-portable way that may work or may not! Alternatively, if you choose to castthe ptr variableto (size_t) instead, then you don't need to worry about the pointer typeanymore. 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). ), Styling contours by colour and by line thickness in QGIS. Asking for help, clarification, or responding to other answers. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. 4. Type Conversions - C in a Nutshell [Book] - O'Reilly Online Learning Find centralized, trusted content and collaborate around the technologies you use most. 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. If the source type is bool, the value false is converted to zero and the value true is converted to the value one of the destination type (note that if the destination type is int, this is an integer promotion, not an integer conversion). Connect and share knowledge within a single location that is structured and easy to search. Re: [PATCH, PR 53001] Re: Patch to split out new warning flag for Use #include to define it. 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 SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); rev2023.3.3.43278. Please help me compile Chez Scheme. use $(ARCHS_STANDARD_32_BIT) at Architecture instead of $(ARCHS_STANDARD). Before I update Xcode, my project still can build and run normally with all devices. Sign in Don't do that. linux c-pthreads: problem with local variables. Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. Then i can continue compiling. C / C++ Forums on Bytes. pthread create managing values generated in function (in c), Establishing TCP socket connection between PHP client and C server on Ubuntu. There's no proper way to cast this to int in general case. Cast unsigned char (uint8 *) pointer to unsigned long (uint32 *) pointer Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. A void pointer can be really useful if the programmer is not sure about the data type of data inputted by the end user. The most general answer is - in no way. A cast converts an object or value from one type to another. Can Martian regolith be easily melted with microwaves? "clang" "-Ilib\libopenvswitch.a.p" "-Ilib" "-I..\lib" "-I." rev2023.3.3.43278. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Or, they are all wrong. Find centralized, trusted content and collaborate around the technologies you use most. All character types are to be converted to an integer. Difficulties with estimation of epsilon-delta limit proof. : iPhone Retina 4-inch 64-bit) is selected. You can use any other pointer, or you can use (size_t), which is 64 bits. 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. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. And then assign it to the double variable. *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 and type conversions - C# Programming Guide @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. Windows has 32 bit long only on 64 bit as well. In this case, casting the pointer back to an integer is meaningless, because . Thanks for contributing an answer to Stack Overflow! Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. what does it mean to convert int to void* or vice versa? To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. Making statements based on opinion; back them up with references or personal experience. A cast specifies a conversion from one type to another. C++ how to get the address stored in a void pointer? ^~~~~~~~~~~~~~~~~~~~~ I don't see how anything bad can happen . how to cascade 2d int array to 2d void pointer array? for saving RAM), use union, and make sure, if the mem address is treated as an int only if you know it was last set as an int. warning C4311: 'type cast': pointer truncation from 'void *' to 'long' in ECPG test files. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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. 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 correct answer is, if one does not mind losing data precision. Whats the grammar of "For those whose stories they are"? Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. 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. What is the difference between const int*, const int * const, and int const *? Where does this (supposedly) Gibson quote come from? @DavidHeffernan, sane thread APIs wouldn't send integral data to the thread procedures, they would send pointers. For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. Based on the design of this function, which modification is right. Can we typecast void into int? - Quora If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. To avoid truncating your pointer, cast it to a type of identical size. Identify those arcade games from a 1983 Brazilian music video. Star 675. error: cast from 'void*' to 'int' loses precision - Stack Overflow Does Counterspell prevent from any further spells being cast on a given turn? I am compiling this program in linux gcc compiler.. How to use Slater Type Orbitals as a basis functions in matrix method correctly? ", "!"? I'm trying to create a void* from an int. I cannot reverse my upvote of user384706's answer, but it's wrong. Most answers just try to extract 32 useless bits out of the argument. In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. 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. casting from int to void* and back to int - C / C++ Asking for help, clarification, or responding to other answers. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? 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). 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. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Such a downcast makes no runtime checks to ensure that the object's runtime type is actually D, and may only be used safely if this precondition is guaranteed by other means, such as when implementing static polymorphism. GitHub. There is absolutely not gurantee that sizeof(int) <= sizeof(void*). My code is all over the place now but I appreciate you all helping me on my journey to mastery! On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. Converts between types using a combination of implicit and user-defined conversions. Please tell me error: cast from 'void*' to 'int' loses precision, How Intuit democratizes AI development across teams through reusability. What is the purpose of this D-shaped ring at the base of the tongue on my hiking boots? In the case of Widening Type Casting, the lower data type (having smaller size) is converted into the higher data type (having larger size). Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? This allows you to reinterpret the void * as an int. While working with Threads in C, I'm facing the warning, "warning: cast to pointer from integer of different size". The subreddit for the C programming language, Press J to jump to the feed. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? Using Kolmogorov complexity to measure difficulty of problems? Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, error: cast from void* to int loses precision, cast to pointer from integer of different size, pthread code. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? The problem is not with casting, but with the target type loosing half of the pointer. 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. If you write ((char*)ptr + 1), it will advance the pointer 1 byte, because a "char" is 1 byte. By clicking Sign up for GitHub, you agree to our terms of service and Whats the grammar of "For those whose stories they are"? The calculated expression consists of two operations. Is a PhD visitor considered as a visiting scholar. The following program casts a double to an int. windows meson: cast to smaller integer type 'unsigned long' from 'void *'. Noncompliant Code Example (memset())For historical reasons, certain C Standard functions accept an argument of type int and convert it to either unsigned char or plain char. SCAN_PUT_ATTR(key, ATTR, skey, FUNC); To learn more, see our tips on writing great answers. Is pthread_join a must when using pthread in linux? 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. 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. Thanks for pointing that out. This will get you a pointer from a 32 bit offset: A function pointer is incompatible to void* (and any other non function pointer). ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Setting a buffer of char* with intermediate casting to int*. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. Implicit Type Conversion in C with Examples - GeeksforGeeks Casting type void to uint8_t - Arduino Forum Casting type void to uint8_t - Arduino Forum 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; "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. Why does flowing off the end of a non-void function without returning a value not produce a compiler error? What does casting to void* does when passing arguments to variadic functions? reinterpret_cast conversion - cppreference.com 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 you do here is undefined behavior, and undefined behavior of very practical sort. All float types are to be converted to double. 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. Implementing From will result in the Into implementation but not vice-versa. this way I convert an int to a void* which is much better than converting a void* to an int. -1, Uggh. It is done by the compiler on its own, without any external trigger from the user. And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. The difference between a and &a is the type. Click to see the query in the CodeQL repository. The only alternative is really to take time and fix all 64-bit code issues, of which there may be some non-trivial issues. vegan) just to try it, does this inconvenience the caterers and staff? reinterpret_cast is a type of casting operator used in C++. AC Op-amp integrator with DC Gain Control in LTspice. Once you manage to make this cast, then what?! "-I.." "-Iinclude\openflow" "-I..\include\openflow" "-Iinclude\openvswitch" "-I..\include\openvsw Yeah, the tutorial is doing it wrong. } SCAN_END_SINGLE(ATTR) x is a local variable and its lifetime ends as soon as control leaves the scope it was defined in. How do I set, clear, and toggle a single bit? 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. What does it mean to convert int to void* or vice versa? Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. static const void* M_OFFSET = (void*)64*1024; Since gcc compiles that you are performing arithmetic between void* and an int ( 1024 ). ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ should we also have a diagnostic for the (presumed) user error? c - How to cast an integer to void pointer? - Stack Overflow
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