For integer casts in specific, using into() signals that . 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. LLNL's tutorial is bad and they should feel bad. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? Sign up for a free GitHub account to open an issue and contact its maintainers and the community. 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. The subreddit for the C programming language, Press J to jump to the feed. Can I tell police to wait and call a lawyer when served with a search warrant? to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj 471,961 Members | 900 Online. Using indicator constraint with two variables. STR34-C. As Ferruccio said, int must be replaced with intptr_t to make the program meaningful. c - type casting integer to void* - Stack Overflow Already on GitHub? Use of Void pointers in C programming language The text was updated successfully, but these errors were encountered: You signed in with another tab or window. Type casting is when you assign a value of one primitive data type to another type. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. what does it mean to convert int to void* or vice versa? long guarantees a pointer size on Linux on any machine. If you write ((char*)ptr + 1), it will advance the pointer 1 byte, because a "char" is 1 byte. I need to convert the argument to an int for later use: The compiler (GCC version 4.2.4) returns the error: You can cast it to an intptr_t type. Casting arguments inside the function is a lot safer. SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); And, most of these will not even work on gcc4. However, I believe that even if the define was for the "65536", it would not be what @kaetzacoatl wanted. iphone - Error "Cast from pointer to smaller type 'int' loses A cast specifies a conversion from one type to another. GitHub. This is memory reinterpretation - a completely unacceptable way to do what the OP is trying to do. Linear regulator thermal information missing in datasheet. In Java, there are two types of casting: Widening Casting (automatically) - converting a smaller type to a larger type size. You may declare a const int variable and cast its reference to the void*. It generally takes place when in an expression more than one data type is present. 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. The most general answer is - in no way. Thanks for contributing an answer to Stack Overflow! Where does this (supposedly) Gibson quote come from? The difference between the phonemes /p/ and /b/ in Japanese. Therefore, you need to change it to long long instead of long in windows for 64 bits. Here, the Java first converts the int type data into the double type. I personally upvoted this answer because by it's first line of text it helped me to understand the reason of this strange error message and what am I, poor idiot, doing :D. Not valid on Windows 64 - long is still 32-bit but pointers are 64-bit. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Casting type void to uint8_t - Arduino Forum 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. Where does this (supposedly) Gibson quote come from? 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; ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' Windows has 32 bit long only on 64 bit as well. 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. this way you won't get any warning. Floating-point conversions even though the compiler doesn't know you only ever pass myFcn to pthread_create in conjunction with an integer. rev2023.3.3.43278. The following program casts a double to an int. What is "cast from integer to pointer of different size" warning? 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. Making statements based on opinion; back them up with references or personal experience. Type Casting in C Language with Examples - Dot Net Tutorials [mst-vhost:vhost 5/52] drivers/block/virtio_blk.c:539:21: warning Don't do that. Usually that means the pointer is allocated with. Why does Mister Mxyzptlk need to have a weakness in the comics? Therefore it is perfectly valid for the compiler to throw an error for a line like. Connect and share knowledge within a single location that is structured and easy to search. 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. Casting Pointers - IBM To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Whats the grammar of "For those whose stories they are"? 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. cast to void *' from smaller integer type 'int clang warnings in v1.42 Issue #265 ocornut/imgui GitHub 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. Not the answer you're looking for? What is the point of Thrower's Bandolier? On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. 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. This is what the second warning is telling you. If you preorder a special airline meal (e.g. How do I set, clear, and toggle a single bit? How do I count the number of sentences in C using ". Since all pointers on 64-bit Windows are 64 bits, you are growing the data size from 32 bits backto 64 bits. If you are going to pass the address you typically need to exert some more control over the lifetime of the object. So,solution #3 works just fine. For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. Can we typecast void into int? - Quora Why do small African island nations perform better than African continental nations, considering democracy and human development? Can Martian regolith be easily melted with microwaves? SCAN_PUT(ATTR, NULL); 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). What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? 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 "After the incident", I started to be more careful not to trip over things. Well occasionally send you account related emails. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' Based on the design of this function, which modification is right. 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; Replacing broken pins/legs on a DIP IC package, How to handle a hobby that makes income in US. Cerror: cast to 'void *' from smaller integer type 'int' (void *)i Error: cast to 'void *' from smaller integer type 'int' PS: UBUNTUCLANG3.5 clang -O0 -std=gnu11 -march=native -lm -lpthread pagerank.c -o pagerank c pthreads 4 10.3k 2 21 2015-06-05 -1, Uggh. arrays - I get the error: "cast to smaller integer type 'int' from I have a function with prototype void* myFcn(void* arg) which is used as the starting point for a pthread. However, you are also casting the result of this operation to (void*). ", "? If any, how can the original function works without errors if we just ignore the warning. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. The cast back to int * is not, though. Notifications. actually no, as int my be a smaller type than a pointer ;-) But, of course with int64_t it works fine. Star 675. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. ), Styling contours by colour and by line thickness in QGIS. vegan) just to try it, does this inconvenience the caterers and staff? This explicit cast clearly tells the compiler "Shut up, I know that this code does not look correct, but I do know what I am doing". Using Kolmogorov complexity to measure difficulty of problems? This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. casting from int to void* and back to int. this way I convert an int to a void* which is much better than converting a void* to an int. (int) pthread_self() 64int48intuintptr_t (unsigned int) The text was updated successfully, but these errors were encountered: x is a local variable and its lifetime ends as soon as control leaves the scope it was defined in. returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); BUT converting a pointer to void* and back again is well supported (everywhere). *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 . Please tell me error: cast from 'void*' to 'int' loses precision, How Intuit democratizes AI development across teams through reusability. This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. @Shahbaz you could but I will not suggest to a C newbie to use globals. ", "!"? Replacing broken pins/legs on a DIP IC package, AC Op-amp integrator with DC Gain Control in LTspice. } SCAN_END_SINGLE(ATTR) You can use any other pointer, or you can use (size_t), which is 64 bits. I'm trying to learn pthreads and thing that keeps bugging me is how do i really pass argument to the function. Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? 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. casting from int to void* and back to int - C / C++ 10) A prvalue of type pointer to void (possibly cv-qualified) can be converted to pointer to any object type. An open (void) pointer can hold a pointer of any type. Difficulties with estimation of epsilon-delta limit proof. If this is the data to a thread procedure, then you quite commonly want to pass by value. Converting a void* to an int is non-portable way that may work or may not! To access the object value, use the * dereference operator: int * p; assert (p == null ); p = new int (5); assert (p != null ); assert (*p == 5); (*p)++; assert (*p == 6); If a pointer contains a null value, it is not pointing to a valid object. Identify those arcade games from a 1983 Brazilian music video, Relation between transaction data and transaction id, The difference between the phonemes /p/ and /b/ in Japanese. error: cast from pointer to smaller type 'unsigned int' loses information. 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. unsigned long call_fn = (unsigned long)FUNC; and how to print the thread id of 2d array argument? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. C99 defines the types "intptr_t" and "uintptr_t" which do . . What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? Clang warnings for an invalid casting? - The FreeBSD Forums Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Disconnect between goals and daily tasksIs it me, or the industry? Java Type Casting. I would create a structure and pass that as void* to pthread_create. But assuming that it is, as long as the caller and the callee agree, you can do that sort of thing. ^~~~~~~~~~~~~~~~~~~~ Well it does this because you are converting a 64 bits pointer to an 32 bits integer so you loose information. The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS.
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