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

As Ferruccio said, int must be replaced with intptr_t to make the program meaningful. What were the most popular text editors for MS-DOS in the 1980s? The next Access Europe Meeting is on Wed 3 May 2023. What does casting to void* does when passing arguments to variadic functions? I agree that you should bite the bullet and fix the code to use the correct integer type. Unfortunately, that hardware is 64-bit and the code contains many instances of pointer arithmetic that expects pointers to be 32-bit, i.e. You are just making it bigger by tricking the compiler and the ABI. What is this brick with a round back and a stud on the side used for? dynamic, and reinterpret casting. @DavidHeffernan, sane thread APIs wouldn't send integral data to the thread procedures, they would send pointers. 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? 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. long guarantees a pointer size on Linux on any machine. 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. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. The -fms-extensions flag resolved the issue. c printf() C , {} . 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. i Definition: C++ introduced a different cast system from C that distinguishes the types of cast operations. Is "I didn't think it was serious" usually a good defence against "duty to rescue"? 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. Did the Golden Gate Bridge 'flatten' under the weight of 300,000 people in 1987? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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). Or keep using a C cast even when C++ code compiled as C++. 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. BUT converting a pointer to void* and back again is well supported (everywhere). Or, they are all wrong. What is the correct method to cast an int to a void*? 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. Casting is required when information might be lost in the conversion, or when the conversion might not succeed for other reasons. Which ability is most related to insanity: Wisdom, Charisma, Constitution, or Intelligence? Asking for help, clarification, or responding to other answers. 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. how about using uintptr_t, most of your pointer arithmetic may still works. The proper way is to cast it to another pointer type. 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]. reinterpret_cast<void *>(42)). 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. Passing negative parameters to a wolframscript, Generating points along line with specifying the origin of point generation in QGIS. How can I control PNP and NPN transistors together from one pin? to the original pointer: The following type designates an unsigned integer type with the The error message mentions the diagnostic responsible for error message, e.g. @ok If this is the data to a thread procedure, then you quite commonly want to pass by value. */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. Yes, for the reason you mentioned that's the proper intermediate type. pointer/reference to a derived class pointer/reference. "jacob navia" wrote: This question has probably been asked a million time, but here it comes 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. Thanks for contributing an answer to Stack Overflow! 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. It is safer to not make assumptions, but rather check the type. 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! 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; By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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. For example, a variable of type long (64-bit integer) can store any value that an int (32-bit integer) can store. My blogs h2 and other tags are in these manner. I am compiling this program in linux gcc compiler.. Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. Join Bytes to post your question to a community of 472,246 software developers and data experts. You may declare a const int variable and cast its reference to the void*. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @Dinesh: could you please 1) show us those. To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. Can you still use Commanders Strike if the only attack available to forego is an attack against an ally? comment:4 by Kurt Schwehr, 8 years ago r28216 removes OGDIDataset:: GetInternalHandle from trunk I wish your idea worked. How to correctly cast a pointer to int in a 64-bit application? 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; It keeps throwing this exact error message even though both types are 32 bits wide. Question is, how do I explain this to Clang? I assumed that gcc makes a 65536 out of my define, but I was wrong. 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. If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, I would try to fix the code instead. 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. It's not them. 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. MIP Model with relaxed integer constraints takes longer to solve than normal model, why? 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. 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'. @jackdoe: It's a waste of human life to write code that "you may need in the future". This is a fine way to pass integers to new pthreads, if that is what you need. This will get you a pointer from a 32 bit offset: A function pointer is incompatible to void* (and any other non function pointer). last post by: I'm looking for the name of the following casting style in order to do The C Standard allows any object pointer to be cast to and from void *. 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. 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. 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). Connect and share knowledge within a single location that is structured and easy to search. Which ability is most related to insanity: Wisdom, Charisma, Constitution, or Intelligence? Now, what happens when I run it with the thread sanitizer? This forum has migrated to Microsoft Q&A. Examples include conversions from smaller to larger integral types, and conversions from derived classes to base classes. Use #include to define it. #, In a 64 bit machine with sizeof(int) == 4. If you need to keep the returned address, just keep it as void*. Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? Short story about swapping bodies as a job; the person who hires the main character misuses his body. 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. @DietrichEpp can you explain what is race condition with using. cast to void *' from smaller integer type 'int-tdecu credit scoretdecu credit score I would like to know the reason. C99 defines the types "intptr_t" and "uintptr_t" which do . This option of Python is missing in matplotlibcpp within Visual Studio -> works only in b/w ! 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. 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. @Martin York: No, it doesn't depend on endiannness. Which was the first Sci-Fi story to predict obnoxious "robo calls"? Did the Golden Gate Bridge 'flatten' under the weight of 300,000 people in 1987? To access the object value, use the * dereference operator: int * p; assert (p == null ); p = new int (5); assert (p != null ); assert (*p == 5); (*p)++; assert (*p == 6); If a pointer contains a null value, it is not pointing to a valid object. I had this error while trying to cross compile the header from libstdc++ 5.4.0 with clang 7.0.1 for ARM. It's an int type guaranteed to be big enough to contain a pointer. Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. The compiler is perfectly correct & accurate! Based on the design of this function, which modification is right. 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. The only exception is exotic systems with the SILP64 data model, where the size of int is also 64 bits. My code is all over the place now but I appreciate you all helping me on my journey to mastery! Solution 1. And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. @ck_ I didn't realize the error in the question is actually an error by default, not a warning-turned-error. Explicit conversions (casts): Explicit conversions require a cast expression. 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 The following program casts a double to an int. Why did DOS-based Windows require HIMEM.SYS to boot? If any, how can the original function works without errors if we just ignore the warning. What does 'They're at four. char **array; But, sure, in that specific case you can pass a local variable address, type casting integer to void* [duplicate]. MIP Model with relaxed integer constraints takes longer to solve than normal model, why? again. The Test method has an Animal parameter, thus explicitly casting the argument a to a Reptile makes a dangerous assumption. casting from int to void* and back to int. Save this piece of code as mycast.hpp and add -include mycast.hpp to your Makefile. rev2023.5.1.43405. You are getting warnings due to casting a void* to a type of a different size. Is it safe to publish research papers in cooperation with Russian academics? Is a downhill scooter lighter than a downhill MTB with same performance? i32 -> u32) is a no-op Casting from a larger integer to a smaller integer (e.g. How to get the error message from the error code returned by GetLastError()? 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 am using the UDF of the Ansys Manual Book as a base for what I intended, but I am trying to incorporate a second component to my condensable mixture, being methanol . One could try -fms-extensions (hopefully not -fms-compatibility), but that would bring all the shebang with it. If you write ((char*)ptr + 1), it will advance the pointer 1 byte, because a "char" is 1 byte. static const void* M_OFFSET = (void*)64*1024; Since gcc compiles that you are performing arithmetic between void* and an int ( 1024 ). Even though what you say regarding the lifetime of the object is true, integral types are too limited for a generic API. rev2023.5.1.43405. Can you still use Commanders Strike if the only attack available to forego is an attack against an ally? linux c-pthreads: problem with local variables. 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. I have a function with prototype void* myFcn(void* arg) which is used as the starting point for a pthread. He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. Don't pass your int as a void*, pass a int* to your int, so you can cast the void* to an int* and copy the dereferenced pointer to your int. Interpreting non-statistically significant results: Do we have "no evidence" or "insufficient evidence" to reject the null? Use returnPtr[j] = (void *) ((long)ptr + i); ). So,solution #3 works just fine. Should I re-do this cinched PEX connection? Does it effect my blogs SEO rankings? But then you need to cast your arguments inside your thread function which is quite unsafe cf. Implementation-dependent. Embedded hyperlinks in a thesis or research paper. Short story about swapping bodies as a job; the person who hires the main character misuses his body. How do I count the number of sentences in C using ". So you know you can cast it back like this. Casting a pointer to void* and back is valid use of reinterpret_cast<>. rev2023.5.1.43405. I'm working on a school project that involves porting a large piece of C++ code on an experimental piece of hardware. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. User without create permission can create a custom object from Managed package using Custom Rest API. (i.e. Generating points along line with specifying the origin of point generation in QGIS. 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). Can my creature spell be countered if I cast a split second spell after it? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Thanks for contributing an answer to Stack Overflow! It seems both static_cast and dynamic_cast can cast a base class Asking for help, clarification, or responding to other answers. 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 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*. . rev2023.5.1.43405. The preprocesor absolutely will not perform arithmetic. How do I force make/GCC to show me the commands? Why is it shorter than a normal address? There is absolutely not gurantee that sizeof(int) <= sizeof(void*). Thanks for contributing an answer to Stack Overflow! You think by casting it here that you are avoiding the problem! If you call your thread creation function like this, then the void* arriving inside of myFcn has the value of the int you put into it. Find centralized, trusted content and collaborate around the technologies you use most. property that any valid pointer to void can be converted to this type, The correct answer is, if one does not mind losing data precision. Not the answer you're looking for? What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. From the question I presume the OP does. What is this brick with a round back and a stud on the side used for? Find centralized, trusted content and collaborate around the technologies you use most. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Why don't we use the 7805 for car phone chargers? I'm not sure how to tell Clang (it's tools, really) that the platform is a 32-bit platform and to stop complaining. (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 To learn more, see our tips on writing great answers. 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. Needless to say, this will still be wrong. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Thanks for pointing that out. some reading around on it and why it is sometimes used. How to set, clear, and toggle a single bit? ', referring to the nuclear power plant in Ignalina, mean? How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. What is this brick with a round back and a stud on the side used for. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. I understood, but that would introduce dynamic memory and ugly lifetime issues (an object allocated by one thread must be freed by some other) - all just to pass an. This thread has been closed and replies have been disabled. What are the advantages of running a power tool on 240 V vs 120 V? 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. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. this question. With that declaration, you can later say: myData = "custom string"; That points the myData pointer to the address of your constant string. This example is noncompliant on an implementation where pointers are 64 bits and unsigned integers are 32 bits because the result of converting the 64-bit ptr cannot be represented in the 32-bit integer type. X* px = new X; For a complete list of all implicit numeric conversions, see the Implicit numeric conversions section of the Built-in numeric conversions article.

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