cast to 'void *' from smaller integer type 'int'

Passing arguments to pthread_create - invalid conversion from void(*)() to void(*)(void*). 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. Canadian of Polish descent travel to Poland with Canadian passport. Both languages have been widely adopted by How to plot text in color? 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. @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. Find centralized, trusted content and collaborate around the technologies you use most. (void *)(long)i, Copyright 2011-2023 SegmentFault. I'm having a little bit of trouble regarding pointer casting in my program. # * # (intptr_t) # # warning: cast to pointer from integer of different size # (intptr_t)IDE # (void*) . 565), Improving the copy in the close modal and post notices - 2023 edition, New blog post from our CEO Prashanth: Community is the future of AI. I have read in one of old posting that don't cast of pointer which I hit this same problem in a project without C++11, and worked around it like this: Thanks for contributing an answer to Stack Overflow! last post by: I'm looking for the name of the following casting style in order to do 565), Improving the copy in the close modal and post notices - 2023 edition, New blog post from our CEO Prashanth: Community is the future of AI. 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. Please start a new discussion. UDF for multiples heterogenous reactions - CFD Online For built-in numeric types, an implicit conversion can be made when the value to be stored can fit into the variable without being truncated or rounded off. MIP Model with relaxed integer constraints takes longer to solve than normal model, why? (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, , i Integer conversions, both implicit and explicit (using a cast), must be guaranteed not to result in lost or misinterpreted data. Thanks for pointing that out. They should do their job unless your code is too tricky. Is there a way to disable it? Is "I didn't think it was serious" usually a good defence against "duty to rescue"? is returned by the malloc. 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. arduino ide - Incompatible types in assignment of 'uint8_t {aka Can I use my Coinbase address to receive bitcoin? Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey, xcode build error: Semantic issue cast from pointer to smaller type 'int' loses information. Then he wants to convert px to Hello, 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;. Use #include to define it. 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. Where can I find a clear diagram of the SPECK algorithm? Basically its a better version of (void *)i. How to correctly cast a pointer to int in a 64-bit application? Convert integers, floating-point values and enum types to enum types. Not the answer you're looking for? There exist two main syntaxes for generic type-casting: functional and c-like: 1 2 3 4 double x = 10.3; int y; y = int (x); // functional notation y = (int) x; // c-like cast notation The functionality of these generic forms of type-casting is enough for most needs with fundamental data types. How to convert a factor to integer\numeric without loss of information? The OP wanted to convert a pointer value to a int value, instead, most the answers, one way or the other, tried to wrongly convert the content of arg points to to a int value. ", "!"? If you really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. How to get the error message from the error code returned by GetLastError()? return ((void **) returnPtr);} /* Matrix() */. c - type casting integer to void* - Stack Overflow Can I use an 11 watt LED bulb in a lamp rated for 8.6 watts maximum? What does 'They're at four. Does a password policy with a restriction of repeated characters increase security? Short story about swapping bodies as a job; the person who hires the main character misuses his body. casting from int to void* and back to int. Could a subterranean river or aquifer generate enough continuous momentum to power a waterwheel for the purpose of producing electricity? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Thanks for contributing an answer to Stack Overflow! Half your pointer will be garbage. a cast of which the programmer should be aware of what (s)he is doing. For example, you might have an integer variable that you need to pass to a method whose parameter is typed as double. Why did US v. Assange skip the court of appeal? I am looking to clean up the Connect and share knowledge within a single location that is structured and easy to search. Why is it shorter than a normal address? Thanks Jonathan, I was thinking about my answer in another thread: AraK is correct, passing integers a pointers are not necessarily interchangeable. Again, all of the answers above missed the point badly. Did the Golden Gate Bridge 'flatten' under the weight of 300,000 people in 1987? In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. If any, how can the original function works without errors if we just ignore the warning. 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; rev2023.5.1.43405. Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey, Setting a buffer of char* with intermediate casting to int*. equal to the original pointer: First you are using a define, which is not a variable. Generating points along line with specifying the origin of point generation in QGIS. Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? It is commonly called a pointer to T and its type is T*. 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. I want to learn the difference between the three type cast operators: Hi, dynamic_cast safely converts pointers and references to classes up, down and sideways along the inheritance hierarchy - according to CppReference. I was able to disable this with -fms-extensions after getting this from someone on the Cpplang Slack: Looking at "DiagnosticSemaKinds.td" it shows up as err_bad_reinterpret_cast_small_int, https://github.com/llvm-mirror/clang/blob/release_50/include/clang/Basic/DiagnosticSemaKinds.td#L6193 I don't see how anything bad can happen . This option of Python is missing in matplotlibcpp within Visual Studio -> works only in b/w ! Can I use my Coinbase address to receive bitcoin? Is a downhill scooter lighter than a downhill MTB with same performance? Type conversion in Java with Examples - GeeksforGeeks Can you still use Commanders Strike if the only attack available to forego is an attack against an ally? Implicit conversions - cppreference.com I think using intptr_t is the correct intermediate here, since it's guaranteed to be large enough to contain the integral value of the void*, and once I have an integer value I can then truncate it without causing the compiler to complain. From that point on, you are dealing with 32 bits. I am running into the same problem where I am using Clang's static analyzer and clang-tidy to scan code on a 64-bit system that is targeted for a 32-bit system. . long guarantees a pointer size on Linux on any machine. 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. Why don't we use the 7805 for car phone chargers? @Xax: Here's a fixed version, without the race condition: gist.github.com/depp/241d6f839b799042c409, gist.github.com/depp/3f04508a88a114734195, How a top-ranked engineering school reimagined CS curriculum (Ep. d=(double *) Hi, C99 defines the types "intptr_t" and "uintptr_t" which do . rev2023.5.1.43405. 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], Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. With that declaration, you can later say: myData = "custom string"; That points the myData pointer to the address of your constant string. MIP Model with relaxed integer constraints takes longer to solve than normal model, why? Casting and type conversions - C# Programming Guide By using Bytes.com and it's services, you agree to our Privacy Policy and Terms of Use. To learn more, see our tips on writing great answers. I think the solution 3> should be the correct one. [PATCH] platform/x86: hp-wmi: Fix cast to smaller integer type warning To learn more, see our tips on writing great answers. casting from int to void* and back to int - C / C++ 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. Mar 30, 2020 at 11:12am Clang warnings for an invalid casting? - The FreeBSD Forums /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. Episode about a group who book passage on a space ship controlled by an AI, who turns out to be a human who can't leave his ship? Connect and share knowledge within a single location that is structured and easy to search. When do you use in the accusative case? How to correctly cast a pointer to int in a 64-bit application? 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 If the data types are compatible, then Java will perform the conversion automatically known as Automatic Type Conversion, and if not then they need to be cast or converted explicitly. To learn more, see our tips on writing great answers. Who has a solution to casting from int to void* and back to int, http://www.ungerhu.com/jxh/clc.welcome.txt, http://benpfaff.org/writings/clc/off-topic.html. For more information, see Polymorphism. Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey. However, this specific error is not due to a warning and I can't find any option to disable errors (makes sense, since most errors are fatal). How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey, error: cast from void* to int loses precision, cast to pointer from integer of different size, pthread code. it means that myData is a variable of type "pointer to uint8_t", but it doesn't point to anything yet. Is a downhill scooter lighter than a downhill MTB with same performance? Type conversions - cplusplus.com Based on the design of this function, which modification is right. @jackdoe: It's a waste of human life to write code that "you may need in the future". Becase one can always legally cast any Hello, How can I control PNP and NPN transistors together from one pin? Interpreting non-statistically significant results: Do we have "no evidence" or "insufficient evidence" to reject the null? 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. is there such a thing as "right to be heard"? It's always a good practice to put your #define's in brackets to avoid such surprise. 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. ), For those who are interested. Unfortunately, that hardware is 64-bit and the code contains many instances of pointer arithmetic that expects pointers to be 32-bit, i.e. pthread create managing values generated in function (in c), Establishing TCP socket connection between PHP client and C server on Ubuntu. How to use Clang static analyzer with a Cortex-M project? 1) zero or one conversion from the following set: lvalue-to-rvalue conversion, array-to-pointer conversion, and function-to-pointer conversion; 2) zero or one numeric promotion or numeric conversion; 3) zero or one function pointer conversion; (since C++17) 4) zero or one qualification conversion. Episode about a group who book passage on a space ship controlled by an AI, who turns out to be a human who can't leave his ship? Passing negative parameters to a wolframscript, Generating points along line with specifying the origin of point generation in QGIS. Nov 14 '05 Since all pointers on 64-bit Windows are 64 bits, you are growing the data size from 32 bits backto 64 bits. Why does Acts not mention the deaths of Peter and Paul? (i.e. I have a function with prototype void* myFcn(void* arg) which is used as the starting point for a pthread. 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. Therefore, you need to change it to long long instead of long in windows for 64 bits. Offline ImPer Westermark over 12 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. Converting a void* to an int is non-portable way that may work or may not! Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, "what happen when typcating normal variable to void* or any pointer variable?" 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. [-Wextra-tokens] (if it doesn't, remove the -fno-diagnostics-show-option flag). Just because you're altering. Say you hack this successfully. this question. 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). I was sent this code and can't figure out why I keep getting "Incomplete Data type Error, Embracing Modern Android Development: A Dive into Java and Kotlin. And, most of these will not even work on gcc4. Since gcc compiles that you are performing arithmetic between void* and an int (1024). c - Cast int to void* - Stack Overflow The next Access Europe Meeting is on Wed 3 May 2023. Question is, how do I explain this to Clang? In the following example, the compiler implicitly converts the value of num on the right to a type long before assigning it to bigNum. When is casting void pointer needed in C? Making statements based on opinion; back them up with references or personal experience. Canadian of Polish descent travel to Poland with Canadian passport, Two MacBook Pro with same model number (A1286) but different year, Folder's list view has different sized fonts in different folders. Asking for help, clarification, or responding to other answers. If you need to keep the returned address, just keep it as void*. If your standard library (even if it is not C99) happens to provide these types - use them. C++ how to get the address stored in a void pointer? 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. For more information, see the Conversions section of the C# language specification. I'm working on a school project that involves porting a large piece of C++ code on an experimental piece of hardware.

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