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. #, In a 64 bit machine with sizeof(int) == 4. If the original type is a void *, converting to an int may lose date on platforms where sizeof(void *) != sizeof(int) (which is true of LP64 programming model). The -fms-extensions flag resolved the issue. Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey. But to answer your question: No, you can't disable it, though you can work around it. How to convert a factor to integer\numeric without loss of information? char **array; rev2023.3.3.43278. how to cascade 2d int array to 2d void pointer array? Asking for help, clarification, or responding to other answers. More info about Internet Explorer and Microsoft Edge, How to convert between hexadecimal strings and numeric types, How to safely cast using pattern matching and the as and is operators. Because C# is statically-typed at compile time, after a variable is declared, it cannot be declared again or assigned a value of another type unless that type is implicitly convertible to the variable's type. Just edited. There is absolutely not gurantee that sizeof(int) <= sizeof(void*). How create a simple program using threads in C? 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. You use the address-of operator & to do that int x = 10; void *pointer = &x; And in the function you get the value of the pointer by using the dereference operator *: int y = * ( (int *) pointer); Share Improve this answer Follow edited Apr 15, 2013 at 13:58 answered Apr 15, 2013 at 13:53 Some programmer dude 396k 35 399 609 1 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. How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. linux c-pthreads: problem with local variables. 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. Technically, these casts should therefore be valid. I can easily imagine a situation where rewriting code using, Disabling "cast from pointer to smaller type uint32_t" error in Clang, https://github.com/llvm-mirror/clang/blob/release_50/include/clang/Basic/DiagnosticSemaKinds.td#L6193, https://github.com/llvm-mirror/clang/blob/release_50/lib/Sema/SemaCast.cpp#L2112, How a top-ranked engineering school reimagined CS curriculum (Ep. 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. Making statements based on opinion; back them up with references or personal experience. The pointer doesn't actually point to anything, but it's the result of an earlier cast from an integer to a pointer (e.g. Extracting arguments from a list of function calls. "
is pointer to interface, not interface" confusion, Cast from uint8_t pointer to uint32_t integer compilation error. i "jacob navia" wrote: This question has probably been asked a million time, but here it comes Not the answer you're looking for? Alternatively, if you choose to castthe ptr variableto (size_t) instead, then you don't need to worry about the pointer typeanymore. dynamic, and reinterpret casting. To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. Yes, for the reason you mentioned that's the proper intermediate type. void* -> integer -> void* rather than integer -> void* -> integer. The only exception is exotic systems with the SILP64 data model, where the size of int is also 64 bits. If you are going to pass the address you typically need to exert some more control over the lifetime of the object. Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey. So,solution #3 works just fine. Canadian of Polish descent travel to Poland with Canadian passport. These kinds of operations are called type conversions. Was Aristarchus the first to propose heliocentrism? How should a standardized and beautiful flowchart be designed? This option of Python is missing in matplotlibcpp within Visual Studio -> works only in b/w ! C / C++ Forums on Bytes. Thanks for contributing an answer to Stack Overflow! 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. OP said he doesn't want it. You can then disable this diagnostic completely by adding -Wno-extra-tokens (again, the "extra tokens" warning is an example), or turn it into a non-fatal warning by means of -Wno-error=extra-tokens. I want to learn the difference between the three type cast operators: Hi, Is pthread_join a must when using pthread in linux? #, Nov 14 '05
rev2023.5.1.43405. This rule is particularly true for integer values that originate from untrusted sources and are used in any of the following ways: Integer operands of any pointer arithmetic, including array indexing Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. It is safer to not make assumptions, but rather check the type. To disable or enable advertisements and analytics tracking please visit the manage ads & tracking page. it often does reinterpret_cast<uint32_t> (ptr). 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. 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 You can use any other pointer, or you can use (size_t), which is 64 bits. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. 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. User without create permission can create a custom object from Managed package using Custom Rest API. again. On most platforms pointers and longs are the same size, but ints and pointers often are not the same size on 64bit platforms. Based on the design of this function, which modification is right. To learn more, see our tips on writing great answers. What does 'They're at four. Connect and share knowledge within a single location that is structured and easy to search. Short story about swapping bodies as a job; the person who hires the main character misuses his body. 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. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. @Martin York: No, it doesn't depend on endiannness. Or, they are all wrong. On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. Why is it shorter than a normal address? But this code pass the normal variable .. Is a downhill scooter lighter than a downhill MTB with same performance? 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? I'm working on a school project that involves porting a large piece of C++ code on an experimental piece of hardware. Mar 30, 2020 at 11:12am Since the culprit is probably something like -Wall which enables many warnings you should keep on, you should selectively disable this single warning. There's no proper way to cast this to int in general case. This allows you to reinterpret the void * as an int. Can my creature spell be countered if I cast a split second spell after it? How a top-ranked engineering school reimagined CS curriculum (Ep. Has the cause of a rocket failure ever been mis-identified, such that another launch failed due to the same problem? 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. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. 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 You are just making it bigger by tricking the compiler and the ABI. The point is (probably) that the value passed to the thread is an integer value, not really a 'void *'. 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). error: request for member '..' in '..' which is of non-class type. He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. I don't see how anything bad can happen . This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s). No sense in writing a few dozen lines of extra code just to get a bunch of numbered threads. Generating points along line with specifying the origin of point generation in QGIS. Use returnPtr[j] = (void *) ((long)ptr + i); ). If the types are from the same inheritance tree, then you should either use dynamic_casts or even better, you should benefit from dynamic dispatching.. dynamic_cast is slightly better, but still should be avoided. Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. By using Bytes.com and it's services, you agree to our Privacy Policy and Terms of Use. 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]. What are the advantages of running a power tool on 240 V vs 120 V? Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey. In some reference type conversions, the compiler cannot determine whether a cast will be valid. Folder's list view has different sized fonts in different folders. 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. how about using uintptr_t, most of your pointer arithmetic may still works. Needless to say, this will still be wrong. I cannot reverse my upvote of user384706's answer, but it's wrong. Then he wants to convert px to Hello, Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul Definition: C++ introduced a different cast system from C that distinguishes the types of cast operations. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. If you need to keep the returned address, just keep it as void*. Passing negative parameters to a wolframscript, Generating points along line with specifying the origin of point generation in QGIS. static const void* M_OFFSET = (void*)64*1024; Since gcc compiles that you are performing arithmetic between void* and an int ( 1024 ). 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. If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . You can use a 64 bits integer instead howerver I usually use a function with the right prototype and I cast the function type : Where can I find a clear diagram of the SPECK algorithm? Making statements based on opinion; back them up with references or personal experience. ", "!"? They should do their job unless your code is too tricky. Is a downhill scooter lighter than a downhill MTB with same performance? What you do here is undefined behavior, and undefined behavior of very practical sort. Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. Why did DOS-based Windows require HIMEM.SYS to boot? For example, the string cannot be implicitly converted to int. A. if(x%2=1)y=x;B. if(sqrt(x)%2)y=x;C. if(x==1)y=x;D. if(x==1)y=&x; Cerror: cast to 'void *' from smaller integer type 'int'. And, most of these will not even work on gcc4. a generic module (say some ADT implementation) that requires a by: William S Fulton |
The reinterpret_cast makes the int the size of a pointer and the warning will stop. 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. 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. 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. If you really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. 472,096 Members | 2,054 Online. It's always a good practice to put your #define's in brackets to avoid such surprise. this way you won't get any warning. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. cwindowccwindowsword[3]={"ab"};_ab charPersondebug, A, A, , "C" ???? Connect and share knowledge within a single location that is structured and easy to search. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. MIP Model with relaxed integer constraints takes longer to solve than normal model, why? Your strategy will not work for stack-allocated objects, be careful!! 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. If the sizes are different then endianess comes into play. Is there any known 80-bit collision attack? This will get you a pointer from a 32 bit offset: A function pointer is incompatible to void* (and any other non function pointer). 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. Expressions Converts between types using a combination of implicit and user-defined conversions. One could try -fms-extensions (hopefully not -fms-compatibility), but that would bring all the shebang with it. C++ how to get the address stored in a void pointer? 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. . or, Array with multiple data types? 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. If you write ((char*)ptr + 1), it will advance the pointer 1 byte, because a "char" is 1 byte. Why does setupterm terminate the program? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, You should be doing int x = *((int *)arg); You are casting from void * to int that is why you get the warning. returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size);
return ((void **) returnPtr);} /* Matrix() */. Is "I didn't think it was serious" usually a good defence against "duty to rescue"? Well it does this because you are converting a 64 bits pointer to an 32 bits integer so you loose information. Does a password policy with a restriction of repeated characters increase security? comment:4 by Kurt Schwehr, 8 years ago r28216 removes OGDIDataset:: GetInternalHandle from trunk pointer/reference to a derived class pointer/reference. rev2023.5.1.43405. I have a question about casting a function pointer. Interpreting non-statistically significant results: Do we have "no evidence" or "insufficient evidence" to reject the null? Which reverse polarity protection is better and why? Can you still use Commanders Strike if the only attack available to forego is an attack against an ally? I'm only guessing here, but I think what you are supposed to do is actually pass the address of the variable to the function. Please tell me error: cast from 'void*' to 'int' loses precision, How a top-ranked engineering school reimagined CS curriculum (Ep. Find centralized, trusted content and collaborate around the technologies you use most. So you could do this: Note: As sbi points out this would require a change on the OP call to create the thread. Can I use an 11 watt LED bulb in a lamp rated for 8.6 watts maximum? 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. Not the answer you're looking for? This is an old C callback mechanism so you can't change that. Why don't we use the 7805 for car phone chargers? 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;. I'm not sure how to tell Clang (it's tools, really) that the platform is a 32-bit platform and to stop complaining. BUT converting a pointer to void* and back again is well supported (everywhere). What is the correct method to cast an int to a void*? How to cast a void pointer to any other type in C || #C Programming language || Coding is Life 487 03 : 37 Unable to cast object of type 'System DateTime' to type 'System String' SharpCoder 336 10 : 53 Tkinter window geometry to manage height width and zoom out using state and resizable () option plus2net 107 Author by david.brazdil There are ways to prevent this: pass a dynamic allocated argument if your not the passing thread is not static or if your argument is a local variable, otherwise there is no issue. Ubuntu won't accept my choice of password, Adding EV Charger (100A) in secondary panel (100A) fed off main (200A), Passing negative parameters to a wolframscript. However, you are also casting the result of this operation to (void*). Rep Power: 3. ), For those who are interested. It seems both static_cast and dynamic_cast can cast a base class Not the answer you're looking for? 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. The following program casts a double to an int. I am looking to clean up the Embedded hyperlinks in a thesis or research paper. 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. Yeah, the tutorial is doing it wrong. following block Hello, Join Bytes to post your question to a community of 472,246 software developers and data experts. Can you still use Commanders Strike if the only attack available to forego is an attack against an ally? Write values of different data types in sequence in memory? Thanks for contributing an answer to Stack Overflow! Casting is required when information might be lost in the conversion, or when the conversion might not succeed for other reasons. This code is a bit odd (but a void* can certainly host a int on all architectures on which GDAL can be compiled), and certainly unused by anyone, so you could just remove the GetInternalHandle () implementation as well if you prefer. 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
Why did US v. Assange skip the court of appeal? # * # (intptr_t) # # warning: cast to pointer from integer of different size # (intptr_t)IDE # (void*) . This returns the first 32 bits of the pointer which may be the top or the bottom depending on big versus little endian, as comment #2 said. 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. Connect and share knowledge within a single location that is structured and easy to search. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. struct foo *foo; Put your define inside a bracket: #define M_TABLE_SIZE (64*1024) Now, you can do: static const void* M_OFFSET = (void*) M_TABLE_SIZE; without a problem. 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. 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. 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. Please start a new discussion. replace uint32_t by uintptr_t wholesale, then fix remaining cases one by one. Were sorry. What is this brick with a round back and a stud on the side used for. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy.
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