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

Hello, I am currently working on a UDF for the heterogeneous reaction using it to describe a simple equilibrium model using the Antoine equation and vapor pressure. dynamic, and reinterpret casting. LLNL's tutorial is bad and they should feel bad. The preprocesor absolutely will not perform arithmetic. converted back to pointer to void, and the result will compare equal It's always a good practice to put your #define's in brackets to avoid such surprise. Your strategy will not work for stack-allocated objects, be careful!! Is a downhill scooter lighter than a downhill MTB with same performance? But to just truncate the integer value and not having to fix all the wrong uses of uint32_t just yet, you could use static_cast(reinterpret_cast(ptr)). Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, I would try to fix the code instead. 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 . Why don't we use the 7805 for car phone chargers? 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. In this case, casting the pointer back to an integer is meaningless, because . 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" (. I've always been a little sketchy on the differences between static, This is not a conversion at all. From: Hans de Goede <hdegoede@redhat.com> To: Mark Gross <mgross@linux.intel.com> Cc: Hans de Goede <hdegoede@redhat.com>, Andy Shevchenko <andy@infradead.org>, platform-driver-x86@vger.kernel.org, kernel test robot <lkp@intel.com> Subject: [PATCH] platform/x86: hp-wmi: Fix cast to smaller integer type warning Date: Mon, 23 Jan 2023 14:28:24 +0100 [thread overview] Message-ID: <20230123132824. . Interpreting non-statistically significant results: Do we have "no evidence" or "insufficient evidence" to reject the null? A nit: in your version, the cast to void * is unnecessary. This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. Embedded hyperlinks in a thesis or research paper. As for the stack, I've written a few libraries using pthreds, thus I don't agree that what you describe "is quite often the case". Why does flowing off the end of a non-void function without returning a value not produce a compiler error? 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 use Clang static analyzer with a Cortex-M project? Canadian of Polish descent travel to Poland with Canadian passport. I think the solution 3> should be the correct one. Explicitly call a single-argument constructor or a conversion operator. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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 Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. void* -> integer -> void* rather than integer -> void* -> integer. Not the answer you're looking for? I have a question about casting a function pointer. 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. this way you won't get any warning. How can I control PNP and NPN transistors together from one pin? For integral types, this means the range of the source type is a proper subset of the range for the target type. long guarantees a pointer size on Linux on any machine. The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function. @ck_ I didn't realize the error in the question is actually an error by default, not a warning-turned-error. a cast of which the programmer should be aware of what (s)he is doing. 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? rev2023.5.1.43405. The most general answer is - in no way. Alternatively, if you choose to castthe ptr variableto (size_t) instead, then you don't need to worry about the pointer typeanymore. pointer/reference to a derived class pointer/reference. Examples include conversions from smaller to larger integral types, and conversions from derived classes to base classes. The compiler is perfectly correct & accurate! Or you might need to assign a class variable to a variable of an interface type. (void *)(long)i, Copyright 2011-2023 SegmentFault. What does casting to void* does when passing arguments to variadic functions? The correct answer is, if one does not mind losing data precision. To learn more, see our tips on writing great answers. I agree passing a dynamically allocated pointer is fine (and I think the best way). The only. You can also convert values from one type to another explicitly using the cast operator (see Chapter 5 ): ( type_name) expression In the following example, the cast operator causes the division of one integer variable by another to be performed as a floating-point operation: int sum = 22, count = 5; double mean = (double)sum / count; In 64-bit programs, the size of the pointer is 64 bits and it cannot be put into the int type that remains 32-bit almost in all the systems. The point is (probably) that the value passed to the thread is an integer value, not really a 'void *'. Visit Microsoft Q&A to post new questions. Many errors come from warnings. Asking for help, clarification, or responding to other answers. 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. or, Array with multiple data types? 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. 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*. This option of Python is missing in matplotlibcpp within Visual Studio -> works only in b/w ! Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. 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? He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. Can you still use Commanders Strike if the only attack available to forego is an attack against an ally? Casting is required when information might be lost in the conversion, or when the conversion might not succeed for other reasons. It is possible for a cast operation that compiles correctly to fail at run time. Save this piece of code as mycast.hpp and add -include mycast.hpp to your Makefile. What is the difference between const int*, const int * const, and int const *? 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, Short story about swapping bodies as a job; the person who hires the main character misuses his body. Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. (i.e. I'm having a little bit of trouble regarding pointer casting in my program. 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. 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. 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; They should do their job unless your code is too tricky. For more information, see the Conversions section of the C# language specification. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Short story about swapping bodies as a job; the person who hires the main character misuses his body. and how to print the thread id of 2d array argument? Join Bytes to post your question to a community of 472,246 software developers and data experts. cwindowccwindowsword[3]={"ab"};_ab charPersondebug, A, A, , "C" ???? 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. You just need to suppress the warning, and this will do it: This may offend your sensibilities, but it's very short and has no race conditions (as you'd have if you used &i). You think by casting it here that you are avoiding the problem! However, you are also casting the result of this operation to (void*). 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. It does not because. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @Dinesh: could you please 1) show us those. For example, the string cannot be implicitly converted to int. Thanks for contributing an answer to Stack Overflow! C / C++ Forums on Bytes. Just edited. It is commonly called a pointer to T and its type is T*. Now, what happens when I run it with the thread sanitizer? is returned by the malloc. Interpreting non-statistically significant results: Do we have "no evidence" or "insufficient evidence" to reject the null? Does a password policy with a restriction of repeated characters increase security? You are right! As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey. In the following example, the compiler implicitly converts the value of num on the right to a type long before assigning it to bigNum. 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. How a top-ranked engineering school reimagined CS curriculum (Ep. Needless to say, this will still be wrong. He also rips off an arm to use as a sword, Two MacBook Pro with same model number (A1286) but different year. If you write ((char*)ptr + 1), it will advance the pointer 1 byte, because a "char" is 1 byte. This is a fine way to pass integers to new pthreads, if that is what you need. Generating points along line with specifying the origin of point generation in QGIS. BUT converting a pointer to void* and back again is well supported (everywhere). I assumed that gcc makes a 65536 out of my define, but I was wrong. I am looking to clean up the For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. Terrible solution. 23.04.27, ICP15005796-233010602002000ICP B2-20201554. u32 -> u8) will truncate Casting from a smaller integer to a larger integer (e.g. Since gcc compiles that you are performing arithmetic between void* and an int (1024). I'm not sure how to tell Clang (it's tools, really) that the platform is a 32-bit platform and to stop complaining. Is a downhill scooter lighter than a downhill MTB with same performance? Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey. The -fms-extensions flag resolved the issue. To disable or enable advertisements and analytics tracking please visit the manage ads & tracking page. In my case, I was using a 32-bit value that needed to be passed to an OpenGL function as a void * representing an offset into a buffer. (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 MIP Model with relaxed integer constraints takes longer to solve than normal model, why? Basically its a better version of (void *)i. I have read in one of old posting that don't cast of pointer which For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. You need to pass an actual pointer. You are just making it bigger by tricking the compiler and the ABI. 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 Solution 1. How a top-ranked engineering school reimagined CS curriculum (Ep. Integer conversions, both implicit and explicit (using a cast), must be guaranteed not to result in lost or misinterpreted data. C99 defines the types "intptr_t" and "uintptr_t" which do . 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! */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); for (i=0, j=0; j returnPtr[j] = (void *) (ptr + i); // <<< Compile Errors, Error1error C2036: 'void *' : unknown sizec:\temp\testone\lib\utils.c57, 2> returnPtr[j] = (void *) ((long*)ptr + i); // <<< No compile errors, 3> returnPtr[j] = (void *) ((char*)ptr + i); // <<< No compile errors. This allows you to reinterpret the void * as an int. elizabeth guevara don ho; how to send coffee truck in korea; masala hut sheraton maldives menu; tennis player died today; 957103591e449b3c6cadab7 luke combs caleb pressley high school; Did the Golden Gate Bridge 'flatten' under the weight of 300,000 people in 1987? Therefore, after you declare i as an int, you cannot assign the string "Hello" to it, as the following code shows: However, you might sometimes need to copy a value into a variable or method parameter of another type. Going through them one by one would be very tedious and since this is an experimental project anyway, I'm happy to settle for a "hackish" workaround. The next Access Europe Meeting is on Wed 3 May 2023. I'm working on a school project that involves porting a large piece of C++ code on an experimental piece of hardware. How to correctly cast a pointer to int in a 64-bit application? 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. error: comparison between pointer and integer ('int' and 'string' (aka 'char *')), CS50 Caesar program is working but check50 says it isn't. returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); Even though what you say regarding the lifetime of the object is true, integral types are too limited for a generic API. How to cast/convert pointer to reference in C++, clang error: unknown argument: '-mno-fused-madd' (python package installation failure). But this code pass the normal variable .. If you convert (void*) to (long) no precision is lost, then by assigning the (long) to an (int), it properly truncates the number to fit. Making statements based on opinion; back them up with references or personal experience. You can use a 64 bits integer instead howerver I usually use a function with the right prototype and I cast the function type : Please help me with the right way to convert void* to int in c++ Mar 30, 2020 at 10:44am George P (5286) Maybe try reinterpret_cast? what does it mean to convert int to void* or vice versa? Thanks in A colleague asked me something along the lines of the following today. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, "what happen when typcating normal variable to void* or any pointer variable?" I cannot reverse my upvote of user384706's answer, but it's wrong. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Is "I didn't think it was serious" usually a good defence against "duty to rescue"? You could use this code, and it would do the same thing as casting ptr to (char*). In the best case this will give the same results as the original code, with no advantages, but in the worst case it will fail in multiple catastrophic ways (type punning, endianness, less efficient, etc. Run this code to find how Java handles division and what casting can do to the results. For more information, see How to convert a byte array to an int, How to convert a string to a number, and How to convert between hexadecimal strings and numeric types. The content you requested has been removed. Which was the first Sci-Fi story to predict obnoxious "robo calls"? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. error: request for member '..' in '..' which is of non-class type. My blogs h2 and other tags are in these manner. i Was Aristarchus the first to propose heliocentrism? Extracting arguments from a list of function calls. Can I use an 11 watt LED bulb in a lamp rated for 8.6 watts maximum? Most answers just try to extract 32 useless bits out of the argument. Nov 14 '05 We have to pass address of the variable to the function because in function definition argument is pointer variable. Both languages have been widely adopted by How to plot text in color? Question is, how do I explain this to Clang? In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. The error message mentions the diagnostic responsible for error message, e.g. 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. Is a downhill scooter lighter than a downhill MTB with same performance? How do I check if a string represents a number (float or int)? OP said he doesn't want it. it means that myData is a variable of type "pointer to uint8_t", but it doesn't point to anything yet. Just because you're altering. Rep Power: 3. Passing arguments to pthread_create - invalid conversion from void(*)() to void(*)(void*). How to convert a factor to integer\numeric without loss of information? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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). Why does setupterm terminate the program? Did the Golden Gate Bridge 'flatten' under the weight of 300,000 people in 1987? The error I'm getting is: error: cast from pointer to smaller type 'uint32_t' (aka 'unsigned int') loses information. User without create permission can create a custom object from Managed package using Custom Rest API. Well it does this because you are converting a 64 bits pointer to an 32 bits integer so you loose information. Or keep using a C cast even when C++ code compiled as C++. How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. Say I want to make Once you manage to make this cast, then what?! And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. This thread has been closed and replies have been disabled. That could create all kinds of trouble. MIP Model with relaxed integer constraints takes longer to solve than normal model, why? If a negative integer value is converted to an unsigned type, the resulting value corresponds to its 2's complement bitwise representation (i.e., If the conversion is from a floating-point type to an integer type, the value is truncated (the decimal part is removed). 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. Explicit conversions (casts): Explicit conversions require a cast expression. Since all pointers on 64-bit Windows are 64 bits, you are growing the data size from 32 bits backto 64 bits. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Use #include to define it. However, if a conversion cannot be made without a risk of losing information, the compiler requires that you perform an explicit conversion, which is called a cast. The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. The only exception is exotic systems with the SILP64 data model, where the size of int is also 64 bits. Is "I didn't think it was serious" usually a good defence against "duty to rescue"? If the result lies outside the range of representable values by the type, the conversion causes, Otherwise, if the conversion is between numeric types of the same kind (integer-to-integer or floating-to-floating), the conversion is valid, but the value is. return ((void **) returnPtr);} /* Matrix() */. Even if you are compiling your program for a 32-bit computer, you should fix your code to remove these warnings, to ensure your code is easily portable to 64-bit. This is not even remotely "the correct answer". Passing negative parameters to a wolframscript, Generating points along line with specifying the origin of point generation in QGIS. 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. C++ how to get the address stored in a void pointer? But, sure, in that specific case you can pass a local variable address, type casting integer to void* [duplicate]. d=(double *) Hi, @Martin York: No, it doesn't depend on endiannness. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. I agree that you should bite the bullet and fix the code to use the correct integer type. Definition: C++ introduced a different cast system from C that distinguishes the types of cast operations. Find centralized, trusted content and collaborate around the technologies you use most. Asking for help, clarification, or responding to other answers. For reference types, an explicit cast is required if you need to convert from a base type to a derived type: A cast operation between reference types does not change the run-time type of the underlying object; it only changes the type of the value that is being used as a reference to that object. You are getting warnings due to casting a void* to a type of a different size. This will get you a pointer from a 32 bit offset: A function pointer is incompatible to void* (and any other non function pointer). But to answer your question: No, you can't disable it, though you can work around it. To avoid truncating your pointer, cast it to a type of identical size. Don't do that. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. Which ability is most related to insanity: Wisdom, Charisma, Constitution, or Intelligence? 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. Should I re-do this cinched PEX connection? Pros: The problem with C casts is the ambiguity of the operation; sometimes you are doing a conversion (e.g., (int)3.5) and sometimes you are doing a cast (e.g., (int)"hello"); C++ casts avoid this. Wrong. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. Making statements based on opinion; back them up with references or personal experience. Generating points along line with specifying the origin of point generation in QGIS. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. No sense in writing a few dozen lines of extra code just to get a bunch of numbered threads. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. So,solution #3 works just fine. If not, check the pointer size on your platform, define these typedefs accordingly yourself and use them. 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.

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