@DavidHeffernan I rephrased that sentence a little. How do I check if a string represents a number (float or int)? While working with Threads in C, I'm facing the warning, "warning: cast to pointer from integer of different size". As a result of the integer division 3/2 we get the value 1, which is of the int type. There's probably little you can do except look or hope for a fixed 2.x version or upgrade to 3.x (I would assume it's 64-bit safe but this is just a guess, do research this issue before you upgrade). The main point is: a pointer has a platform dependent size. C99 defines the types "intptr_t" and "uintptr_t" which do . The calculated expression consists of two operations. what does it mean to convert int to void* or vice versa? C++ how to get the address stored in a void pointer? I don't see how anything bad can happen . "After the incident", I started to be more careful not to trip over things. Remembering to delete the pointer after use so that we don't leak. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? Yeah, the tutorial is doing it wrong. how to cascade 2d int array to 2d void pointer array? How to use Slater Type Orbitals as a basis functions in matrix method correctly? (void *)i Error: cast to 'void *' from smaller integer type 'int'. How do I set, clear, and toggle a single bit? Put your define inside a bracket: without a problem. If you are going to pass the address you typically need to exert some more control over the lifetime of the object. Once you manage to make this cast, then what?! */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. lexborisov Modest Public. Is a PhD visitor considered as a visiting scholar. Properly casting a `void*` to an integer in C++ 24,193 Solution 1 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. windows meson: cast to smaller integer type 'unsigned long' from 'void *'. So make sure you understand what you are doing! this way I convert an int to a void* which is much better than converting a void* to an int. rev2023.3.3.43278. Casting type void to uint8_t - Arduino Forum 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. Alternatively, if you choose to castthe ptr variableto (size_t) instead, then you don't need to worry about the pointer typeanymore. Create an account to follow your favorite communities and start taking part in conversations. You are getting warnings due to casting a void* to a type of a different size. By clicking Sign up for GitHub, you agree to our terms of service and The problem just occur with Xcode 5.1. Functions return bigint only if the parameter expression is a bigint data type. Already on GitHub? For integer casts in specific, using into() signals that . ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' There's no proper way to cast this to int in general case. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). FAILED: lib/libopenvswitch.a.p/odp-util.c.obj For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. 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 How to use Slater Type Orbitals as a basis functions in matrix method correctly? } SCAN_END_SINGLE(ATTR) Only the following conversions can be done with static_cast, except when such conversions would cast away constness or volatility. You could use this code, and it would do the same thing as casting ptr to (char*). Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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). sound/soc/codecs/tlv320aic32x4.c:1202:18: warning: cast to smaller error: cast from pointer to smaller type 'unsigned int' loses information. What does casting to void* does when passing arguments to variadic functions? Asking for help, clarification, or responding to other answers. Projects. Making statements based on opinion; back them up with references or personal experience. Taking the above declarations of A, D, ch of the . Find centralized, trusted content and collaborate around the technologies you use most. As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). Api says this is how i should create thread: So if I want to pass an int what I think I should do is: The second example assumes that a pointer is wide enough to store an int. Therefore, you need to change it to long long instead of long in windows for 64 bits. For the Nozomi from Shinagawa to Osaka, say on a Saturday afternoon, would tickets/seats typically be available - or would you need to book? However even though their types are different, the address is going to be the same. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' Find centralized, trusted content and collaborate around the technologies you use most. [that could be a TODO - not to delay solving the ICE]. SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); You are getting warnings due to casting a void* to a type of a different size. However, I believe that even if the define was for the "65536", it would not be what @kaetzacoatl wanted. 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. The proper way is to cast it to another pointer type. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. C++ Tutorial => Conversion between pointer and integer In such condition type conversion (type promotion) takes place to avoid loss of data. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ If the original pointer value represents an address of a byte in memory that does not satisfy the alignment requirement of the target type, then the resulting pointer value is unspecified. Then i can continue compiling. How do I count the number of sentences in C using ". How to get the error message from the error code returned by GetLastError()? Sign in Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? Can I tell police to wait and call a lawyer when served with a search warrant? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. then converted back to pointer to void, and the result will compare arrays - I get the error: "cast to smaller integer type 'int' from Using Kolmogorov complexity to measure difficulty of problems? This is an old C callback mechanism so you can't change that. XCode 5.1 is change all architecture to 64 bit. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? The nature of simulating nature: A Q&A with IBM Quantum researcher Dr. Jamie We've added a "Necessary cookies only" option to the cookie consent popup. For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. Implicit Type Conversion is also known as 'automatic type conversion'. Cast unsigned char (uint8 *) pointer to unsigned long (uint32 *) pointer You cannot just cast the 32-bit variable to a pointer, because that pointer on a 64-bit machine is twice as long. - the incident has nothing to do with me; can I use this this way? But I'm nitpicking .. Error while setting app icon and launch image in xcode 5.1. Just edited. But the problem has still happened. byte -> short -> char -> int -> long -> float -> double. And, most of these will not even work on gcc4. What is the point of Thrower's Bandolier? @Shahbaz you could but I will not suggest to a C newbie to use globals. 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). It was derived from the BCPL, and the name of the b language is possibly from the BCPL contraction. You are just making it bigger by tricking the compiler and the ABI. "clang" "-Ilib\libopenvswitch.a.p" "-Ilib" "-I..\lib" "-I." From that point on, you are dealing with 32 bits. Type conversions - cplusplus.com No idea how it amassed 27 upvotes?! The following program casts a double to an int. clang warnings in v1.42 Issue #265 ocornut/imgui GitHub However, you are also casting the result of this operation to (void*). whether it was an actual problem is a different matter though. : iPhone Retina 4-inch 64-bit) is selected. Can Martian regolith be easily melted with microwaves? 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. What you do here is undefined behavior, and undefined behavior of very practical sort. 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" (. Can we typecast void into int? - Quora Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. B programing language is a language based on basic combined programming or a BCPL, and it is the precursor of the C programming language. 1. Casting type void to uint8_t - Arduino Forum (int*)Pc = pa; After the execution of the above code all the three pointers, i.e., Pa, Pd, and Pc, point to the value 150. BUT converting a pointer to void* and back again is well supported (everywhere). Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? Well it does this because you are converting a 64 bits pointer to an 32 bits integer so you loose information. This is memory reinterpretation - a completely unacceptable way to do what the OP is trying to do. 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. In a 64bit build a pointer is 64bit (contrary to a 32bit build, where it is 32bit), while an int is 32bit, so this assignment stores a 64bit value in a 32bit storage, which may result in a loss of information. To learn more, see our tips on writing great answers. cast operators [edit] When an expression is used in the context where a value of a different type is expected, conversionmay occur: intn =1L;// expression 1L has type long, int is expectedn =2.1;// expression 2.1 has type double, int is expectedchar*p =malloc(10);// expression malloc(10) has type void*, char* is expected Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul If you preorder a special airline meal (e.g. Number Type Cast | Qt Forum How create a simple program using threads in C? @DavidHeffernan, sane thread APIs wouldn't send integral data to the thread procedures, they would send pointers. For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. The program can be set in such a way to ask the user to inform the type of data and . 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. 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. In such a case the programmer can use a void pointer to point to the location of the unknown data type. From the question I presume the OP does. Disconnect between goals and daily tasksIs it me, or the industry? It is purely a compile-time directive which instructs the compiler to treat expression as if it had . Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Xcode 5 and iOS 7: Architecture and Valid architectures, xcode build error: Semantic issue cast from pointer to smaller type 'int' loses information, Issues in handling touches on subviews(uiviews) in UIScrollView, Architecture linking error after Xcode 5.1 upgrade, iOS 7.1 gives error after updating to Xcode 5.1, Linker error in Xcode 5.1 with cocos2d-x 3 beta 2. Connect and share knowledge within a single location that is structured and easy to search. This will get you a pointer from a 32 bit offset: A function pointer is incompatible to void* (and any other non function pointer). The point is (probably) that the value passed to the thread is an integer value, not really a 'void *'. what happens when we typecast normal variable to void* or any pointer variable? This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. What is "cast from integer to pointer of different size" warning? Find centralized, trusted content and collaborate around the technologies you use most. // OK: lvalue denoting the original d object, // UB: the b subobject is not a base class subobject, // 6. array-to-pointer followed by upcast, https://en.cppreference.com/mwiki/index.php?title=cpp/language/static_cast&oldid=147983, when converting a 'pointer to object' to 'pointer to, the conversion from floating-point values, the conversion from bit-fields to rvalue references, the conversion from integral or enumeration values to enumeration, the conversion from integral or enumeration values to, the conversion from a member of base class type to, a standard-layout class object with no data members, a non-standard-layout union object and a non-static data, for base-to-derived pointer conversions and, the conversion to enumeration types with fixed underlying type, a standard-layout class might have a non-pointer-interconvertible, If the underlying type is not fixed, the behavior is undefined if the value of, If the underlying type is fixed, the result is the same as, one is a union object and the other is a non-static data member of that object, or. ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast]

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