equal to the original pointer. The warning of cast from pointer to integer of different size occurs when you try to save the value of an integer to a pointer variable, as demonstrated in the code below. The problem is that converting a void* pointer to unsigned int is inherently non-portable. Warning: Cast From Pointer to Integer of Different Size in C++ The compiler issues warnings and errors to inform the programmer that something is wrong with the code. There is a error in you code, when you convert the int to a void* calling the pthead_create function, you should convert it back to an integer type. The compiler issues warnings and errors to inform the programmer that something is wrong with the code. Counterexamples to differentiation under integral sign, revisited. (And there are arguments for and against casting the return from, You may have 64-bit pointers, but you are probably still using 32-bit ints. I'm not sure if this is what you want. Using flutter mobile packages in flutter web. The compiler tries to warn you that you lose bits when casting from void * to int. error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast] 1 answer 10 views. Of course here the compiler can clearly see that youre not doing this, and it would be nice if it were smart enough to avoid the warning in cases like this, but its not. cast from pointer to integer of different size [-Wpointer-to-int-cast] I want to calculate the image size in colors in (Mo) and in black and white in (Ko) so for this I'm using a parameters that are past in a terminal command which are (image length and width) #include <stdio.h> #include <stdlib.h> #include <string.h> #include <math.h> int main . Does the collective noun "parliament of owls" originate in "parliament of fowls"? You cannot cast a uint8_t into a char* and expect it to write out the string representation of it. A better idea might be to use intptr_t. This type has the same size of a pointer (not int) in every architecture. Here is my code: main.cpp: In function 'int main()': main.cpp:104:65: warning: cast to pointer from integer of different size Press J to jump to the feed. How to resolve: "cast to pointer from integer of different size" warning in C code? When you try to deference it, you will likely get an segmentation fault. This type has the same size of a pointer (not int) in every architecture. Why do I get "cast from pointer to integer of different size" error? On a lot of systems, sizeof (long) == sizeof (void *). Asking for help, clarification, or responding to other answers. Is it correct to say "The glue on the back of the sticker is dying down so I can not stick the sticker to the wall"? However, there is not guarantee that the size of int is the same of the size of intptr_t, but it's really unlikely that some data is lost in the conversion process. I wouldn't suggest a double cast. You need to include to have the uintptr_t type (an integral type with the same size as a pointer). I mean, why do I get this warning, though the same line compiles w/o any warning on windows & debian? Connect and share knowledge within a single location that is structured and easy to search. The compiler returns a warning because you are converting an int to void * which may have different size, ( but in fact in your machine they have the same size). How to fix "Headers already sent" error in PHP, Why does Typescript say this variable is "referenced. Required fields are marked *. Press question mark to learn the rest of the keyboard shortcuts One thing that is useful to remember is that in a 64 bit system, a pointer is a 64 bit value [a memory address. In 64-bit programs, the pointer size is 64-bit and cannot be set to type int, which is always 32-bit on almost all systems. How to use GIT commands for clone, push, add, commit,, What does a "Cannot find symbol" or "Cannot resolve symbol". 0 comments commented on Jul 22, 2015 Sign up for free to join this conversation on GitHub . Is there any reason on passenger airliners not to have a physical lock between throttles? and then be converted back to that type with a value that compares If its computations can be done with pointers, then do them . When should i use streams vs just accessing the cloud firestore once in flutter? Find centralized, trusted content and collaborate around the technologies you use most. Are you sure it's an error and not a warning? The second one isn't going to be any better. You are passing the local variable i as an argument for runner, sizeof(void*) == 8 and sizeof(int) == 4 (64 bits). Code The following code shows this conversion: int data = 999; // the integer Sign in to comment Assignees No one assigned Labels None yet Projects None yet Milestone No milestone Development It's impossible to absolutely know what the value being stored by that pointer is unless you can guarantee that you set the pointer and it's value/type is unchanged. Would it be possible, given current technology, ten years, and an infinite amount of money, to construct a 7,000 foot (2200 meter) aircraft carrier? Do non-Segwit nodes reject Segwit transactions with invalid signature? next prev parent reply other threads:[~2021-09-18 4:45 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-09-15 13:50 [PATCH] sh: pgtable-3level: Fix cast to pointer from integer of different size Geert Uytterhoeven 2021-09-15 13:58 ` Daniel Palmer 2021-09-15 13:58 ` Daniel Palmer 2021-09-16 12:06 . If you want to pass i, you should wrap it as a pointer or something: You may just want i, and in that case, the following should be safe (but far from recommended): I'm learning Pthreads. Anytime you try to assign a 64-bit value in to a 32-bit value without explicitly casting it the compiler will throw a warning [granted, it could still work but in general is not good practice. First, if you can fix func (are allowed to modify its source), then fix it. How does the Chameleon's Arcane/Divine focus interact with magic item crafting? reinterpret_cast is just like a cast but it resized it so the compile doesn't complain. The message in codeblocks is: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]. What does "Could not find or load main class" mean? Yes, this is not a pthreads issue, it's just massively, massively wrong C all the way down. The reason for the warning is that the compiler suspects you might be trying to round-trip a pointer through int and back. program intermittently stuck with main reporting a different thread id as opposed to the thread itself. I'm trying to create a struct that can hold generic values. This was common practice before the advent of 64-bit machines and it is not safe or reasonable. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Already have an account? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, If you're going to use void pointers, use them to store pointers, not integers. Hi, I was compiling . Any comments? X11 example getting a character out of addr and then setting XTPOINTER to it. How to connect 2 VMware instance running on same Linux host machine via emulated ethernet cable (accessible via mac address)? The text was updated successfully, but these errors were encountered: Is the EU Border Guard Agency able to tell Russian passports issued in Ukraine or Georgia from the legitimate ones? ], int is only a 32-bit value, regardless of what architecture you're on. The best way to do this is by using the intptr_t type. You've got lots of problems with the code you posted. But using. Pro*C to C: cast to pointer from integer of different size [-Wint-to-pointer-cast] and note: in definition of macro 'TEND' format %lu expects argument of type 'long unsigned int' but argument 3 has type long long unsigned int, cast from printer to integer of different size We used to just (void*) the value and the older compilers were happy, but the new versions, for example g++ 4.8.5, know the value is not the right size for a pointer. assignment makes pointer from integer without a cast Note the "without a cast" part. Why would Henry want to close the breach? Ive inserted following preprocessor lines: The reason for the warning is that the compiler suspects you might be trying to round-trip a pointer through int and back. Like @JonathanLeffler said, use uintptr_t. 82,223 Solution 1. Hence, a warning is issued. Are defenders behind an arrow slit attackable? Thanks for contributing an answer to Stack Overflow! How would you create a standalone widget from this widget tree? Bug#622206: libomxvorbis: FTBFS on *64: cast from pointer to integer of different size. A double cast would solve this (int)(uintptr_t)t->key. cast to pointer from integer of different size [-Wint-to-pointer-cast] Submitted: 2018-02-27 18:22 UTC: Modified: 2018-02-27 18:45 UTC: Votes: 4: Avg. We and our partners use cookies to Store and/or access information on a device.We and our partners use data for Personalised ads and content, ad and content measurement, audience insights and product development.An example of data being processed may be a unique identifier stored in a cookie. Why is this usage of "I've to work" so awkward? return makes integer from pointer without a cast [-Wint-conversion] return candidate. Was the ZX Spectrum used for number crunching? We do not currently allow content pasted from ChatGPT on Stack Overflow; read our policy here. How do I print out the contents of a vector? Use %p. Not the answer you're looking for? (Or less likely, vice versa!). However, be very very careful when doing things like this. Connect and share knowledge within a single location that is structured and easy to search. It first casts void * to uintptr_t (same size, no warning), then uintptr_t to int (number to number, no warning). It doesn't know that the void * is actually an int cast, so the lost bits are meaningless. cast to pointer from integer of different size, pthread code, http://man7.org/linux/man-pages/man3/pthread_create.3.html. @AlexanderL.Belikoff I edited the question, @HotLicks I changed the sentence to pthread_create(&thread_id[i], NULL, prod, &thread_id[i]); but I get this error: "Segmentation fault (core dumped)". Is MethodChannel buffering messages until the other side is "connected"? The above code generates a warning or an error, depending on the compiler type. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. The C standard does not specify this. We can save the address of var in this pointer variable, not the value. The only exception is for exotic systems with the SILP64 data model, where the size of int is also 64 bits. oh sorry, it is a warning, but still when I execute the code I get:Segmentation fault (core dumped), @user2908749 Someone can, that someone may be you. Your node just holds some pointers (ADDRESSES), it doesn't hold any VALUES. How to change background color of Stepper widget to transparent color? c pointers gcc-warning. if your compiler does not provide the above definition, use this alternative: What you're coding is that the number itself shall be interpreted as a pointer into memory - so if you have tempC = 23, it will try to go to memory address 23 and try and print a string from there (that is, print all bytes until a 0x00 byte is found). 1 - warning: cast from pointer to integer of different size . Mathematica cannot find square roots of some matrices? If you were to use such an implementation, the program wouldn't work. Why does the USA not have a constitutional court? Irreducible representations of a product of two groups, Disconnect vertical tab connector from PCB. Please consider formatting your code and referencing the line number giving you this error. However if 'i' changes then all the threads have a pointer to the same version. whenComplete() method not working as expected - Flutter Async, iOS app crashes when opening image gallery using image_picker. So you can do something like this: I sort of hacked it up. I'm not sure what you expected to happen, but you are storing the ADDRESS not the VALUE. The first one wasn't necessarily necessary. rev2022.12.9.43105. How do I arrange multiple quotations (each with multiple lines) vertically (with a line through the center) so that they're side-by-side? It is defined as follows : Integer type capable of holding a value converted from a void pointer and then be converted back to that type with a value that compares equal to the original pointer. This type of conversion is wrong for some reasons: ptr is a pointer-type variable used to save the addresses. Because compiling you code I have got a warning. the OP will also have to be careful not to do something like this in a function. note: my compiler options are -std=c99 -Werror -save-temps (same on all three systems). By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. To learn more, see our tips on writing great answers. edit 1: Thanks for everyone replied. Warning: Cast From Pointer to Integer of . :warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] : int 32bit64bit432bit464bit8 At what point in the prequels is it revealed that Palpatine is Darth Sidious? Some of our partners may process your data as a part of their legitimate business interest without asking for consent. Central limit theorem replacing radical n with n. Is energy "equal" to the curvature of spacetime? Therefore, cleaning your code from all the warnings and errors is advised before executing it. The idea behind what you are doing is an integer is 4 bytes and a pointer is 4 bytes in x86_32 (8 bytes in x86_64) so I can convert an integer type to a pointer type and then convert it back to an int type without losing any data. I'm not even sure if this is the correct way to go about it. Consider what you're passing to your thread proc (an promoted. How to check if widget is visible using FlutterDriver. Disconnect vertical tab connector from PCB, QGIS expression not working in categorized symbology. Your email address will not be published. Platform: Vivado 2018.3 and a ZCU102 board In my bare metal code for an A53 core in the Zynq UltraScale+ MPSoC, I get the warning : "cast to pointer from integer of different size [-Wint-to-pointer-cast]' the warning pops-up on the line "bramP = (u32 *)bramBaseAddr;" (see full code below) ><p>In this line I try to assign the base address read from the bramInstance to a pointer to memory by . To learn more, see our tips on writing great answers. pthread_join:warning: cast from pointer to integer of different size? The following line (pure c) compiles cleanly on windows (win7 64 bits + codeblocks 13 + mingw32) and debian (wheezy 32 bits + codeblocks 10 + gcc) but raises warning on kali (64 bits + codeblocks + gcc). Ying-Chun Liu (PaulLiu) Tue, 12 Apr 2011 19:57:16 -0700 The errors forbid the code from executing, whereas warnings allow the execution of the code, but sometimes this execution can cause some memory handling issues. Better way to check if an element only exists in one array. Is it appropriate to ignore emails from a student asking obvious questions? Asking for help, clarification, or responding to other answers. . newsockfddint . But it gives me a warning on compilation. This works in the majority of the scenarios, but there is not guarantee that a pointer and an integer have the same size. 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 ints would be "on the stack" and invalid once the function returns. Different execution orders cause differences in performance of a Pthread program. 12 Solutions to Java 11 package javax.xml.bind does not. int threadnumber = (intptr_t) param; and pthread_create (& (tid [i]), &attr, runner, (void *) (intptr_t) i ); Solution 2 pthread _create (& (tid[i]), &attr, runner, (void *) i); Is the EU Border Guard Agency able to tell Russian passports issued in Ukraine or Georgia from the legitimate ones? Please let me know if there is a proper way to do this. warning: cast from pointer to integer of different size, warning: data definition has no type or storage class, Error : format'%s' expects argument of type 'char *', but argument 2 has type 'int' [-Wformat=], Suppressing "ISO C99 requires rest arguments to be used", GCC warning "incompatible implicit declaration of built-in function printf" under Mac OS X Snow Leopard, warning: variable set but not used [-Wunused-but-set-variable], GCC -Wuninitialized / -Wmaybe-uninitialized issues, Error: this statement may fall through [-Werror=implicit-fallthrough=], Warning: cast to/from pointer from/to integer of different size. Furthermore, the type of the offsetof() expression should be size_t.You should either: use the standard offsetof macro from <stddef.h>. @JoshPetitt, For overcoming strict compiler warnings, the double cast may be necessary. One thing that is useful to remember is that in a 64 bit system, a pointer is a 64 bit value [a memory address.] Add a new light switch in line with another switch? To view the purposes they believe they have legitimate interest for, or to object to this data processing use the vendor list link below. I would consider to rewrite the code for the matrix multiplication because the algorithm is wrong. The possible difference in size is only part of the problem. Thanks for contributing an answer to Stack Overflow! Japanese girlfriend visiting me in Canada - questions at border control? So, this line is wrong : Consider this example where the argument for the thread function is zero. This is on a 64-bit system. (i.e. Manage SettingsContinue with Recommended Cookies. Just wanted to provide a quick fix for the OP's issue for passing a unique arg (in this case the value of i) per thread, which isn't incorrect. In C, please don't cast the return value of malloc (). - unwind Feb 5, 2013 at 15:53 3 If you're going to use void pointers, use them to store pointers, not integers. int i, r; if the thread function is working on a chunks of the matrix, there is not point to go through all the values of the matrix A and B. You might want only the internal loop which, in theory, should work on the part of matrix assigned to it. Not sure if it was just me or something she sent to the whole team. Ready to optimize your JavaScript with Rust? compiler warning - cast from pointer to integer of different size. The warning is often displayed as an error on different compilers. In the above example it's likely 'i' is the index into the thread_id array. See here: http://www.cplusplus.com/reference/cstdio/printf/. I don't know what is wrong.I am new to pthread, and this is what I have made so far: You are wrongly using an hack to pass an integer to a thread. A quick hacky fix might just to cast to long instead of int. PSE Advent Calendar 2022 (Day 11): The other side of Christmas. Did neanderthals need vitamin C from the diet? Correct way to achieve this is by referencing the variable "i" (check http://man7.org/linux/man-pages/man3/pthread_create.3.html): You want to cast integer, short, or char and set a pointer to that value use the reinterpret_cast() call. Received a 'behavior reminder' from manager. I have this code for matrix multiplication, using pthreads, but I get the error "cast to pointer from integer of different size". We can do the following to solve this error. Find centralized, trusted content and collaborate around the technologies you use most. The code below works but I'm getting a compiler warning about the cast from pointer to integer. This means it can point to some memory location, and that memory location can have some value saved. This is a pointer to the address zero. That part of the problem can be solved by using uintptr_t, a type . Unless you add an enum field or something that stores the type of value stored at the pointer location-- but that kind of defeats the purpose. What is this fallacy: Perfection is impossible, therefore imperfection should be overlooked. reduced: void f() { unsigned short i = 0; void* p = (void*)i; } this warns in 32-bit or 64-bit mode using the C compiler, and is controlled by this option that g++ doesn't support: -Wno-int-to-pointer-cast (C and Objective-C only) Suppress warnings from casts to pointer type of an integer of a different size. There is a chance you are losing precision. TabBar and TabView without Scaffold and with fixed Widget. ], If you're not averse to using unsigned integers, it might be easier to use uint_64t or something like that, which will avoid the 64-bit to 32-bit assignment (uint_64t is an unsigned 64-bit int). You'd need an array of integers the same size as the thread_id array, populate it with the indexes and pass a pointer to that integer in instead. If you would like to change your settings or withdraw consent at any time, the link to do so is in our privacy policy accessible from our home page. On a lot of systems, sizeof(long) == sizeof(void *). - Jonathan Leffler Do non-Segwit nodes reject Segwit transactions with invalid signature? @JoshPetitt, you're right that I offered the easy solution, not to fundamental one. unsigned int offset = (uintptr_t) dst % blkLen; You'll need to include stdint.h or inttypes.h to have uintptr_t available. Of course here the compiler can clearly see that you're not doing this, and it would be nice if it were smart . (This example code has been taken from : How to cast an integer to void pointer?). Why is apparent power not measured in watts? When printing pointers, print pointers. Where does the idea of selling dragon parts come from? We do not currently allow content pasted from ChatGPT on Stack Overflow; read our policy here. Solution 2. How to set a newcommand to be incompressible by justification? P thread - cast to pointer from integer of different size, Cast from pointer to integer of different size, cast to pointer from integer of different size -wint-to-pointer-cast, Passing argument as int to thread - Warning: cast to pointer from integer different size. Your platform has pointers that are larger than 32 bits. Help us identify new roles for community members, Proposing a Community-Specific Closure Reason for non-English content. uboot warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] Writel(val, reg) reg = val regint * egint reg=0xFF00FF00 You need to include <stdint.h> to have the uintptr_t type (an integral type with the same size as a pointer). To subscribe to this RSS feed, copy and paste this URL into your RSS reader. edit 2: Though Ive managed to have it compiled w/o warning using the preprocessor lines below, @Keith Thompson (see below) has a crucial point about the issue. The most common operating systems (Windows, Linux, macOS) use the LP64 and LLP64 data models, where int is 32 bits. The consent submitted will only be used for data processing originating from this website. As all the replies note, the problem is a 32 bits vs 64 bits issue. How to resolve: "cast to pointer from integer of different size" warning in C code? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Would salt mines, lakes or flats be reasonably found in high, snowy elevations? Site design / logo 2022 Stack Exchange Inc; user contributions licensed under CC BY-SA. A clean alternative that avoids the warning, and another much nastier issue of wrong result when the converted value is negative, is: Youll need to include stdint.h or inttypes.h to have uintptr_t available. Finally, your compiler is right in warning you. Check stash content before applying in GIT - Code Example. Therefore, it cannot save int-type data in itself. Can code that is valid in both C and C++ produce different behavior when compiled in each language? Not the answer you're looking for? Making statements based on opinion; back them up with references or personal experience. Notify me of follow-up comments by email. Thus you can make gcc silent by casting (without changing the behaviour): some_struct *ptr = (void*)func (); Then, you will get your warning ("cast to pointer from integer of different size") iff the return type of func does not fit for addresses. Making statements based on opinion; back them up with references or personal experience. Data is lost upon conversion from a larger number (int) to a smaller number (pointer). Integer type capable of holding a value converted from a void pointer and then be converted back to that type with a value that compares equal to the original pointer. So you can do something like this: #include <stdint.h> void *threadfunc(void *param) { int id = (intptr_t) param; . } So, my last decision is using uintptr_t would be a better choice. The errors forbid the code from executing, whereas warnings allow the execution of the code, but sometimes this execution can cause some memory handling issues. The only alternative is to design the data structures differently, which is better, but not always applicable. Help us identify new roles for community members, Proposing a Community-Specific Closure Reason for non-English content, warning: cast to pointer from integer of different size [-Wint-to-pointer-cast], Warning: assignment makes pointer from integer without a cast, warning: return makes pointer from integer without a cast but returns integer as desired. The threads won't necessarily read their own index value since it might have been incremented before the thread starts to execute. rev2022.12.9.43105. It first casts void * to uintptr_t (same size, no warning), then uintptr_t to int (number to number, no warning). Solution 1 A quick hacky fix might just to cast to long instead of int. I agree that this is not the ideal way to do this, however, its not incorrect either. (And there are arguments for and against casting the return from malloc (); you don't have to avoid it, but you should know why you do or do not do the casting.) This quick article is about the solution to the warning of cast from pointer to integer of different size in C++. It is defined as follows : Integer type capable of holding a value converted from a void pointer Your email address will not be published. Are the S&P 500 and Dow Jones Industrial Average securities? Secondly, the size of both the variables is different, so there is a chance of data loss in case of this conversion. Site design / logo 2022 Stack Exchange Inc; user contributions licensed under CC BY-SA. Should I give a brutally honest feedback on course evaluations? Here you have allocated the node, but you have not allocated anything to hold the contents. Ready to optimize your JavaScript with Rust? Solution. Why do I have to "git push --set-upstream origin "? Cast to pointer from integer of different size? you are setting your key as a pointer to the contents of address 3, and the value as a pointer to the contents of address 5). This was common practice before the advent of 64-bit machines and it is not safe or reasonable. My code executes the way I want it to, I'm able to use it. Would salt mines, lakes or flats be reasonably found in high, snowy elevations? For example, if the pointers in a system are stored in 16 bits, but integers are stored in 8 bits, a total of 8 bits would be lost in the given conversion. 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