This page has been accessed 1,655,678 times. You can use a 64 bits integer instead howerver I usually use a function with the right prototype and I cast the function type : What is the correct method to cast an int to a void*? Infact I know several systems where that does not hold. Is pthread_join a must when using pthread in linux? Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. Taking the above declarations of A, D, ch of the . Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. The difference between a and &a is the type. ^~~~~~~~~~~~~~~~~~~ privacy statement.
Cerror: cast to 'void *' from smaller integer type 'int' 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. use $(ARCHS_STANDARD_32_BIT) at Architecture instead of $(ARCHS_STANDARD). Then i can continue compiling. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. A missing cast in the new fast > enumeration code. 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;. Replacing broken pins/legs on a DIP IC package, AC Op-amp integrator with DC Gain Control in LTspice. We have to pass address of the variable to the function because in function definition argument is pointer variable. On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. 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. What video game is Charlie playing in Poker Face S01E07? */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j;
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. If you cast an int pointer int, you might get back a different integer. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. Does melting sea ices rises global sea level? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? I'm trying to create a void* from an int. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? This is memory reinterpretation - a completely unacceptable way to do what the OP is trying to do. warning C4311: 'type cast': pointer truncation from 'void *' to 'long' in ECPG test files. Converts between types using a combination of implicit and user-defined conversions. XCode 5.1 is change all architecture to 64 bit.
windows meson: cast to 'HANDLE' (aka 'void *') from smaller integer Asking for help, clarification, or responding to other answers. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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.
Clang warnings for an invalid casting? - The FreeBSD Forums Remembering to delete the pointer after use so that we don't leak. How to get the error message from the error code returned by GetLastError()? what does it mean to convert int to void* or vice versa? Otherwise, if the original pointer value points to an object a, and there is an object b of the . Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? How do I align things in the following tabular environment? 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)). 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. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? @Shahbaz you could but I will not suggest to a C newbie to use globals. If your standard library (even if it is not C99) happens to provide these types - use them. By clicking Sign up for GitHub, you agree to our terms of service and It is purely a compile-time directive which instructs the compiler to treat expression as if it had . Most answers just try to extract 32 useless bits out of the argument. Using Kolmogorov complexity to measure difficulty of problems? This is an old C callback mechanism so you can't change that.
Why did Ukraine abstain from the UNHRC vote on China?
arrays - I get the error: "cast to smaller integer type 'int' from By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. This solution is in accordance with INT18-C. GitHub. Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. As Ferruccio said, int must be replaced with intptr_t to make the program meaningful. This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. ../lib/odp-util.c:5489:33: note: expanded from macro 'SCAN_PUT_ATTR' ncdu: What's going on with this second size column? ^~~~~~~~~~~~~~~~~~~~ If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. how to cascade 2d int array to 2d void pointer array? return ((void **) returnPtr);} /* Matrix() */.
Implicit conversions - cppreference.com Using Kolmogorov complexity to measure difficulty of problems? This page was last modified on 12 February 2023, at 18:25.
Implicit Type Conversion in C with Examples - GeeksforGeeks Keep in mind that thrArg should exist till the myFcn() uses it. Casting arguments inside the function is a lot safer. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. @Martin York: No, it doesn't depend on endiannness. Functions return bigint only if the parameter expression is a bigint data type.
Type conversions - cplusplus.com I need to cast the int from the first function so that I can use it as an argument for the second function. The dynamic_cast<>operator provides a way to check the actual type of a pointer to a polymorphic class. Once you manage to make this cast, then what?! I have looked around and can't seem to find any information on how to do this. ncdu: What's going on with this second size column? Floating-point conversions
byte -> short -> char -> int -> long -> float -> double. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. what does it mean to convert int to void* or vice versa? casting from int to void* and back to int. Thanks Jonathan, I was thinking about my answer in another thread: AraK is correct, passing integers a pointers are not necessarily interchangeable.
this way you won't get any warning.
I'm new to coding and am trying to implement a simple program on my own, that prompts the user the number of residents in an apt complex, the prompts the user to enter the names and apt numbers of each resident. To learn more, see our tips on writing great answers. The preprocessor will replace your code by this: This is unlikely what you are trying to do. 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). Pd = Pa; Similarly, Pc may be type cast to type int and assigned the value Pa. 1. What is the point of Thrower's Bandolier? Thus as a result it may be less error prone to generate a pointer dynamcially and use that. Connect and share knowledge within a single location that is structured and easy to search. and how to print the thread id of 2d array argument? Hence there is no loss in data. How can this new ban on drag possibly be considered constitutional? Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes?
Casting type int to const void* - C / C++ for (i=0, j=0; j
clang warnings in v1.42 Issue #265 ocornut/imgui GitHub C/C++ , Cerror: cast to 'void *' from smaller integer type 'int'. Windows has 32 bit long only on 64 bit as well. Since gcc compiles that you are performing arithmetic between void* and an int (1024). vegan) just to try it, does this inconvenience the caterers and staff? (int) pthread_self() 64int48intuintptr_t (unsigned int) For example, the main thread could wait for all of the other threads to end before terminating. error: cast from pointer to smaller type 'unsigned int' loses information. Using indicator constraint with two variables. itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" Is a PhD visitor considered as a visiting scholar. Thanks for contributing an answer to Stack Overflow! 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. 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. There is absolutely not gurantee that sizeof(int) <= sizeof(void*). It was derived from the BCPL, and the name of the b language is possibly from the BCPL contraction. What is the point of Thrower's Bandolier? 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! [that could be a TODO - not to delay solving the ICE]. 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. 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). But the problem has still happened. The main point is: a pointer has a platform dependent size. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. Do new devs get fired if they can't solve a certain bug? STR34-C. Why do small African island nations perform better than African continental nations, considering democracy and human development? Thanks for contributing an answer to Stack Overflow! 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. I have a function with prototype void* myFcn(void* arg) which is used as the starting point for a pthread. 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. An object pointer (including void*) or function pointer can be converted to an integer type using reinterpret_cast. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Type casting is when you assign a value of one primitive data type to another type. In this case, casting the pointer back to an integer is meaningless, because . You should perform type conversion based on 64bit build system because the type "int" supports only -32768 ~ 32768. 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. Re: [PATCH, PR 53001] Re: Patch to split out new warning flag for Safe downcast may be done with dynamic_cast. @DavidHeffernan I rephrased that sentence a little. 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. 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. Wrong. static_cast conversion - cppreference.com Such pointers can be stored in 32-bit data types (for instance, int, DWORD). But I'm nitpicking .. Find centralized, trusted content and collaborate around the technologies you use most. How do I set, clear, and toggle a single bit? If this is the data to a thread procedure, then you quite commonly want to pass by value. this way you won't get any warning. Converting a pointer to an integer whose result cannot represented in the integer type is undefined behavior is C and prohibited in C++. "clang" "-Ilib\libopenvswitch.a.p" "-Ilib" "-I..\lib" "-I." When is casting void pointer needed in C? : iPhone Retina 4-inch 64-bit) is selected. SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); Next, when doing pointer arithmetic, the addition operation will use the pointer's type to determine how many bytes to add to it when incrementing it. Does a summoned creature play immediately after being summoned by a ready action? property that any valid pointer to void can be converted to this type, 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. ^~~~~~~~~~~~~~~~~~~~~ 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. Find centralized, trusted content and collaborate around the technologies you use most. Why is there a voltage on my HDMI and coaxial cables? A cast specifies a conversion from one type to another. 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;. The point is (probably) that the value passed to the thread is an integer value, not really a 'void *'. I understood, but that would introduce dynamic memory and ugly lifetime issues (an object allocated by one thread must be freed by some other) - all just to pass an. What is the purpose of non-series Shimano components? 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). Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @Dinesh: could you please 1) show us those. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. rev2023.3.3.43278. Does Counterspell prevent from any further spells being cast on a given turn? pthread passes the argument as a void*. 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. Implicit conversions - cppreference.com 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. So make sure you understand what you are doing! For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. Then I build my project, I get the error "Cast from pointer to smaller type 'int' loses information" in EAGLView.mm file (line 408) when 64-bit simulators (e.g. Where does this (supposedly) Gibson quote come from? even though the compiler doesn't know you only ever pass myFcn to pthread_create in conjunction with an integer. 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. [mst-vhost:vhost 5/52] drivers/block/virtio_blk.c:539:21: warning This is a fine way to pass integers to new pthreads, if that is what you need. - the incident has nothing to do with me; can I use this this way? reinterpret_cast conversion - cppreference.com Implementing From will result in the Into implementation but not vice-versa. It's an int type guaranteed to be big enough to contain a pointer. Now, what happens when I run it with the thread sanitizer? The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. B programing language is a language based on basic combined programming or a BCPL, and it is the precursor of the C programming language. @jackdoe: It's a waste of human life to write code that "you may need in the future". [Solved] Properly casting a `void*` to an integer in C++ What happens if you typecast as unsigned first? A nit: in your version, the cast to void * is unnecessary. 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. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? int, bigint, smallint, and tinyint (Transact-SQL) - SQL Server 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 Can we typecast void into int? - Quora Disconnect between goals and daily tasksIs it me, or the industry? *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 . So,solution #3 works just fine. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Setting a buffer of char* with intermediate casting to int*. I cannot reverse my upvote of user384706's answer, but it's wrong. What does casting to void* does when passing arguments to variadic functions? Typically, long or unsigned long is . 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. Mutually exclusive execution using std::atomic? If not, check the pointer size on your platform, define these typedefs accordingly yourself and use them. 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. I'm trying to learn pthreads and thing that keeps bugging me is how do i really pass argument to the function. 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. The subreddit for the C programming language, Press J to jump to the feed. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? 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. The value of float variable is= 37.75. 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. My code is all over the place now but I appreciate you all helping me on my journey to mastery! ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ vegan) just to try it, does this inconvenience the caterers and staff? Casting type void to uint8_t - Arduino Forum How to Cast a void* ponter to a char without a warning? Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. But this code pass the normal variable .. The text was updated successfully, but these errors were encountered: So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Asking for help, clarification, or responding to other answers. 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" (. Notifications. And when assigning to a void pointer, all type information is lost. Cast unsigned char (uint8 *) pointer to unsigned long (uint32 *) pointer Pull requests. This is what the second 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 *)'. 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). Compile error on Android ARM Issue #163 cisco/ChezScheme 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. static_cast on the other hand should deny your stripping away the const qualifier. In simple example code like this it's very easy to convince yourself that there's no problem, but in more elaborate real-world scenarios it's very easy to make this mistake inadvertently. 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 to convert a factor to integer\numeric without loss of information? 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 Error while setting app icon and launch image in xcode 5.1. And then assign it to the double variable. I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . How to notate a grace note at the start of a bar with lilypond? Yeah, the tutorial is doing it wrong. casting from int to void* and back to int - C / C++ You think by casting it here that you are avoiding the problem! You need to pass an actual pointer. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Making statements based on opinion; back them up with references or personal experience. 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. 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 [.]) Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. From the question I presume the OP does. If you are going to pass the address you typically need to exert some more control over the lifetime of the object. The cast back to int * is not, though. Thanks for contributing an answer to Stack Overflow! Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul