May 15, 2023
by cast to 'void *' from smaller integer type 'int'
What does casting to void* does when passing arguments to variadic functions? Were sorry. Posted on Author Author return ((void **) returnPtr);} /* Matrix() */. Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey. It's not them. Mar 30, 2020 at 11:12am Convert integers, floating-point values and enum types to enum types. So,solution #3 works just fine. 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. Yes, for the reason you mentioned that's the proper intermediate type. How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. No idea how it amassed 27 upvotes?! Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. char **array; There are two occurences in "SemaCast.cpp" -- one of which suggests it's sensitive to MS extensions, https://github.com/llvm-mirror/clang/blob/release_50/lib/Sema/SemaCast.cpp#L2112 What I am saying is that it would be safer to use new(5) rather than 5 and deal with it appropriately at the other end. Has the cause of a rocket failure ever been mis-identified, such that another launch failed due to the same problem? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Is "I didn't think it was serious" usually a good defence against "duty to rescue"? Can you still use Commanders Strike if the only attack available to forego is an attack against an ally? Is a downhill scooter lighter than a downhill MTB with same performance? If you need to keep the returned address, just keep it as void*. 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" (. Asking for help, clarification, or responding to other answers. Instead of using a long cast, you should cast to size_t. You think by casting it here that you are avoiding the problem! 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. Asking for help, clarification, or responding to other answers. Is "I didn't think it was serious" usually a good defence against "duty to rescue"? Not the answer you're looking for? The -fms-extensions flag resolved the issue. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Please tell me error: cast from 'void*' to 'int' loses precision, How a top-ranked engineering school reimagined CS curriculum (Ep. The most general answer is - in no way. But gcc always give me a warning, that i cannot cast an int to a void*. what does it mean to convert int to void* or vice versa? C# provides the is operator to enable you to test for compatibility before actually performing a cast. Can you still use Commanders Strike if the only attack available to forego is an attack against an ally? Thanks in A colleague asked me something along the lines of the following today. This will get you a pointer from a 32 bit offset: A function pointer is incompatible to void* (and any other non function pointer). 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; that any valid pointer to void can be converted to this type, then Save this piece of code as mycast.hpp and add -include mycast.hpp to your Makefile. Needless to say, this will still be wrong. @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. 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). I need to execute a SQL Server stored procedure from Java/Spring, and the SP has a try/catch block that logs errors to a table. 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. linux c-pthreads: problem with local variables. 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? Thus as a result it may be less error prone to generate a pointer dynamcially and use that. This thread has been closed and replies have been disabled. You can insert some debugging/logging logic to Reinterpret_cast if necessary. The following program casts a double to an int. 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 Not the answer you're looking for? comment:4 by Kurt Schwehr, 8 years ago r28216 removes OGDIDataset:: GetInternalHandle from trunk Nov 14 '05
this way you won't get any warning. You are right! Don't do that. property that any valid pointer to void can be converted to this type, 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. @DavidHeffernan I rephrased that sentence a little. Two MacBook Pro with same model number (A1286) but different year. 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). Connect and share knowledge within a single location that is structured and easy to search. Even though what you say regarding the lifetime of the object is true, integral types are too limited for a generic API. 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. @ck_ I didn't realize the error in the question is actually an error by default, not a warning-turned-error. What you do here is undefined behavior, and undefined behavior of very practical sort. 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! Storage management is an important module of database, which can be subdivided into memory management and external memory management. u32 -> u8) will truncate Casting from a smaller integer to a larger integer (e.g. The point is (probably) that the value passed to the thread is an integer value, not really a 'void *'. Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. Why are players required to record the moves in World Championship Classical games? On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. When is casting void pointer needed in C? 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. 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. It does not because. The only exception is exotic systems with the SILP64 data model, where the size of int is also 64 bits. Which was the first Sci-Fi story to predict obnoxious "robo calls"? Expressions Converts between types using a combination of implicit and user-defined conversions. Is a downhill scooter lighter than a downhill MTB with same performance? cwindowccwindowsword[3]={"ab"};_ab charPersondebug, A, A, , "C" ???? I'll edit accordingly. u8 -> u32) will zero-extend if the source is unsigned sign-extend if the source is signed How to force Unity Editor/TestRunner to run at full speed when in background? 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)). For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. Did the Golden Gate Bridge 'flatten' under the weight of 300,000 people in 1987? How do I work around the GCC "error: cast from SourceLocation* to int loses precision" error when compiling cmockery.c? Offline ImPer Westermark over 12 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. long guarantees a pointer size on Linux on any machine. 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). If any, how can the original function works without errors if we just ignore the warning. it often does reinterpret_cast(ptr). 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. 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 By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. If you do this, you have the thread reference a value that (hopefully still) lives in some other thread. Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul Wrong. This is not even remotely "the correct answer". again. It's always a good practice to put your #define's in brackets to avoid such surprise. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. #, In a 64 bit machine with sizeof(int) == 4. If your code has the chance to ever be ported to some platform where this doesn't hold, this won't work. Does a password policy with a restriction of repeated characters increase security? Did the Golden Gate Bridge 'flatten' under the weight of 300,000 people in 1987? Widening or Automatic Type Conversion Youll be auto redirected in 1 second. 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*. Please start a new discussion. 472,096 Members | 2,054 Online. Did the Golden Gate Bridge 'flatten' under the weight of 300,000 people in 1987? And in this context, it is very very very common to see programmers lazily type cast the. For a complete list of all implicit numeric conversions, see the Implicit numeric conversions section of the Built-in numeric conversions article. For example, you might have an integer variable that you need to pass to a method whose parameter is typed as double. Connect and share knowledge within a single location that is structured and easy to search. Find centralized, trusted content and collaborate around the technologies you use most. Does it effect my blogs SEO rankings? (i.e. Making statements based on opinion; back them up with references or personal experience. I get the error: "cast to smaller integer type 'int' from 'string' (aka 'char *')" referencing line of code: while (isalpha(residents[i].name) == 0), How a top-ranked engineering school reimagined CS curriculum (Ep. Which reverse polarity protection is better and why? @ok Since the culprit is probably something like -Wall which enables many warnings you should keep on, you should selectively disable this single warning. I would create a structure and pass that as void* to pthread_create. As Ferruccio said, int must be replaced with intptr_t to make the program meaningful. Most answers just try to extract 32 useless bits out of the argument. It seems both static_cast and dynamic_cast can cast a base class @DavidHeffernan, sane thread APIs wouldn't send integral data to the thread procedures, they would send pointers. User-defined conversions: User-defined conversions are performed by special methods that you can define to enable explicit and implicit conversions between custom types that do not have a base classderived class relationship. As a result, it is possible to silently convert from one pointer type to another without the compiler diagnosing the problem by storing or casting a pointer to void * and then storing or casting it to the final type. Can my creature spell be countered if I cast a split second spell after it? is there such a thing as "right to be heard"? 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. Thanks for contributing an answer to Stack Overflow! Asking for help, clarification, or responding to other answers. Or you might need to assign a class variable to a variable of an interface type. If not, check the pointer size on your platform, define these typedefs accordingly yourself and use them. As shown in the following example, a type cast that fails at run time will cause an InvalidCastException to be thrown. I agree passing a dynamically allocated pointer is fine (and I think the best way). The C Standard allows any object pointer to be cast to and from void *. The next Access Europe Meeting is on Wed 3 May 2023. MIP Model with relaxed integer constraints takes longer to solve than normal model, why? How can I control PNP and NPN transistors together from one pin? reinterpret_cast<void *>(42)). Casting arguments inside the function is a lot safer. The program will not compile without the cast. Keep in mind that thrArg should exist till the myFcn() uses it. Alternatively, if you choose to castthe ptr variableto (size_t) instead, then you don't need to worry about the pointer typeanymore. Thanks Jonathan, I was thinking about my answer in another thread: AraK is correct, passing integers a pointers are not necessarily interchangeable. 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. . Windows has 32 bit long only on 64 bit as well. Using an integer address (like &x) is probably wrong, indeed each modification you will execute on x will affect the pass behaviour. From the question I presume the OP does. this way I convert an int to a void* which is much better than converting a void* to an int. Find centralized, trusted content and collaborate around the technologies you use most. Why does Acts not mention the deaths of Peter and Paul? -1, Uggh. 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. What is this brick with a round back and a stud on the side used for? But, sure, in that specific case you can pass a local variable address, type casting integer to void* [duplicate]. Could a subterranean river or aquifer generate enough continuous momentum to power a waterwheel for the purpose of producing electricity? some reading around on it and why it is sometimes used. They should do their job unless your code is too tricky. 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. Interpreting non-statistically significant results: Do we have "no evidence" or "insufficient evidence" to reject the null? Extracting arguments from a list of function calls. Yeah, the tutorial is doing it wrong. Making statements based on opinion; back them up with references or personal experience. 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. Did the drapes in old theatres actually say "ASBESTOS" on them? How do I count the number of sentences in C using ". The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function. Embedded hyperlinks in a thesis or research paper. To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. 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. there How should an excellent flowchart be drawn? . For more information, see User-defined conversion operators. How to correctly cast a pointer to int in a 64-bit application? Connect and share knowledge within a single location that is structured and easy to search. This is flat out wrong. rev2023.3.3.43278. Get the address of a callback function to call dynamically in C++, error: call of overloaded function ambiguous, error: cast from to unsigned int loses precision [-fpermissive]. To learn more, see our tips on writing great answers. Technically, these casts should therefore be valid. But to answer your question: No, you can't disable it, though you can work around it. Folder's list view has different sized fonts in different folders. Why does setupterm terminate the program? He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. 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; Did the drapes in old theatres actually say "ASBESTOS" on them? For example, (double) 1/3 will give a double result instead of an int one. To avoid truncating your pointer, cast it to a type of identical size. (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 10.8k 2 21 2015-06-05 Conversions with helper classes: To convert between non-compatible types, such as integers and System.DateTime objects, or hexadecimal strings and byte arrays, you can use the System.BitConverter class, the System.Convert class, and the Parse methods of the built-in numeric types, such as Int32.Parse.
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