Is it possible to create a concave light? 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 new to coding and am trying to implement a simple program on my own, that prompts the user the number of residents in an apt complex, the prompts the user to enter the names and apt numbers of each resident. Does melting sea ices rises global sea level? a is of type int[4], which can be implicitly cast to int* (ie, a pointer to an int) &a is of type int(*)[4] (ie: a pointer to an array of 4 ints). Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. this way you won't get any warning. should we also have a diagnostic for the (presumed) user error? (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 10.3k 2 21 2015-06-05 Implicit conversions - cppreference.com If that happens soon after the call to pthread_create() then you have a race condition, because there's a chance that the thread will attempt to read x's value after it's life has ended, which invokes undefined behavior. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. C++ how to get the address stored in a void pointer? Any expression can be cast to type void (which means that the result of the expression is ignored), but it's not legal to cast an expression of type void to type int not least because the result of such a cast wouldn't make any sense. Note the difference between the type casting of a variable and type casting of a pointer. [that could be a TODO - not to delay solving the ICE]. No sense in writing a few dozen lines of extra code just to get a bunch of numbered threads. Thanks for contributing an answer to Stack Overflow! To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Sign in Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @Dinesh: could you please 1) show us those. @Shahbaz you could but I will not suggest to a C newbie to use globals. Thank you all for your feedback. This is why you got Error 1 C2036, from your post. Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. cast to 'double *' from smaller integer type 'unsigned int' The C compiler is gcc, clang version 3.9.1, target aarch64--linux-android, thread model posix. However the actual code in question contains an explicit c-style cast to int. Java Type Casting. 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). I assumed that gcc makes a 65536 out of my define, but I was wrong. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? Mutually exclusive execution using std::atomic? How do I set, clear, and toggle a single bit? Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? That could create all kinds of trouble. Functions return bigint only if the parameter expression is a bigint data type. On all of them int is 32bit, not 16bit. Clang warnings for an invalid casting? - The FreeBSD Forums Connect and share knowledge within a single location that is structured and easy to search. Why is this sentence from The Great Gatsby grammatical? How do I count the number of sentences in C using ". You can fix this error by replacing this line of code. 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. Type conversions - cplusplus.com 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; Casting Pointers - IBM 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], Minimising the environmental effects of my dyson brain. How to correctly cast a pointer to int in a 64-bit application? 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. : iPhone Retina 4-inch 64-bit) is selected. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. If the object expression refers or points to is actually a base class subobject of an object of type D, the result refers to the enclosing object of type D. Otherwise, the behavior is undefined: When the target type is bool (possibly cv-qualified), the result is false if the original value is zero and true for all other values. And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. 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, Acidity of alcohols and basicity of amines. Cast unsigned char (uint8 *) pointer to unsigned long (uint32 *) pointer There's no proper way to cast this to int in general case. error: cast from pointer to smaller type 'unsigned int' loses information. It is done by the compiler on its own, without any external trigger from the user. Can Martian regolith be easily melted with microwaves? 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. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. what does it mean to convert int to void* or vice versa? How to correctly cast a pointer to int in a 64-bit application? then converted back to pointer to void, and the result will compare 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; ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' You need to cast the void* pointer to a char* pointer - and then dereference that char* pointer to give you the char that it points to! I agree passing a dynamically allocated pointer is fine (and I think the best way). sound/soc/codecs/tlv320aic32x4.c:1202:18: warning: cast to smaller Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. Making statements based on opinion; back them up with references or personal experience. It solved my problem too. To learn more, see our tips on writing great answers. You need to pass an actual pointer. Can I tell police to wait and call a lawyer when served with a search warrant? How to correctly cast a pointer to int in a 64-bit application? If it's anything like cocos2d-iphone v2.x and just based on this slice of code in a core class I wager it's safe to say that cocos2d-x 2.x also is not compatible with 64 bit code, and you can expect all kinds of issues (not just compile-time but also runtime). 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. windows meson: cast to smaller integer type 'unsigned long' from 'void windows meson: cast to 'HANDLE' (aka 'void *') from smaller integer The cast back to int * is not, though. ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] Using Kolmogorov complexity to measure difficulty of problems? Half your pointer will be garbage. However even though their types are different, the address is going to be the same. This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. I'm using cocos2d-x-2.2.2. Already on GitHub? Update: Today, i download the latest version of cocos2d-x (cocos2d-x 2.2.3). Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? Connect and share knowledge within a single location that is structured and easy to search. 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). Find centralized, trusted content and collaborate around the technologies you use most. But gcc always give me a warning, that i cannot cast an int to a void*. What is the purpose of this D-shaped ring at the base of the tongue on my hiking boots? 10) A prvalue of type pointer to void (possibly cv-qualified) can be converted to pointer to any object type. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. How to Cast a void* ponter to a char without a warning? This is not a conversion at all. Or, they are all wrong. Not the answer you're looking for? Just edited. @BlueMoon Thanks a lot! How can this new ban on drag possibly be considered constitutional? 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. The preprocessor will replace your code by this: This is unlikely what you are trying to do. If your standard library (even if it is not C99) happens to provide these types - use them. Casting type void to uint8_t - Arduino Forum warning C4311: 'type cast': pointer truncation from 'void *' to 'long' in ECPG test files. Type Casting Of Pointers in C - Computer Notes Where does this (supposedly) Gibson quote come from? Casting int to void* : r/C_Programming - reddit - the incident has nothing to do with me; can I use this this way? "because the type "int" supports only -32768 ~ 32768" This is not true for any modern desktop or mobile OS or any OS that is targeted by cocos2d-x. Not the answer you're looking for? For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. Most answers just try to extract 32 useless bits out of the argument. In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. XCode 5.1 is change all architecture to 64 bit. So reinterpret_cast has casted it to long type and then static_cast safely casts long to int, if you are ready do truncte the data. ^~~~~~~~~~~~~~~~~~~ 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). In the case of Widening Type Casting, the lower data type (having smaller size) is converted into the higher data type (having larger size). ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] Connect and share knowledge within a single location that is structured and easy to search. For integer casts in specific, using into() signals that . To learn more, see our tips on writing great answers. Actions. (void *)i Error: cast to 'void *' from smaller integer type 'int'. Thanks. And then assign it to the double variable. Alternatively, if you choose to castthe ptr variableto (size_t) instead, then you don't need to worry about the pointer typeanymore. This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. STR34-C. Cast characters to unsigned char before converting to larger x is a local variable and its lifetime ends as soon as control leaves the scope it was defined in. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. with ids being an array of ints and touch being a pointer. Fix for objc/45925 Hence there is no loss in data. Disconnect between goals and daily tasksIs it me, or the industry? c - How to cast an integer to void pointer? - Stack Overflow We have to pass address of the variable to the function because in function definition argument is pointer variable. Windows has 32 bit long only on 64 bit as well. 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. ../lib/odp-util.c:5489:33: note: expanded from macro 'SCAN_PUT_ATTR' Use returnPtr[j] = (void *) ((long)ptr + i); ). Is a PhD visitor considered as a visiting scholar. AC Op-amp integrator with DC Gain Control in LTspice. I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. -1, Uggh. How do I check if a string represents a number (float or int)? From the question I presume the OP does. @DavidHeffernan, sane thread APIs wouldn't send integral data to the thread procedures, they would send pointers. 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. This is a fine way to pass integers to new pthreads, if that is what you need. Put your define inside a bracket: without a problem. How to use Slater Type Orbitals as a basis functions in matrix method correctly? how to cascade 2d int array to 2d void pointer array? An object pointer (including void*) or function pointer can be converted to an integer type using reinterpret_cast. Yeah, the tutorial is doing it wrong. Does Counterspell prevent from any further spells being cast on a given turn? How to correctly type cast (void*)? - social.msdn.microsoft.com This page was last modified on 12 February 2023, at 18:25. Converting a pointer to an integer whose result cannot represented in the integer type is undefined behavior is C and prohibited in C++. Wrong. Pull requests. 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. Why is this sentence from The Great Gatsby grammatical? You could use this code, and it would do the same thing as casting ptr to (char*). 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. Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul Floating-point conversions I am an entry level C programmer. vegan) just to try it, does this inconvenience the caterers and staff? Casting type int to const void* - C / C++ Usually that means the pointer is allocated with. I don't see how anything bad can happen . SCAN_PUT(ATTR, NULL); Then i can continue compiling. Using indicator constraint with two variables. returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. And, most of these will not even work on gcc4. I have a function with prototype void* myFcn(void* arg) which is used as the starting point for a pthread. I'm unfamiliar with XCode, but the solution should be something like follows: Most of the "solutions" above can lose part of the pointer address when casting to a smaller type. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. You are just making it bigger by tricking the compiler and the ABI. This is an old C callback mechanism so you can't change that. How to convert a factor to integer\numeric without loss of information? 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.
cast to void *' from smaller integer type 'int
cast to void *' from smaller integer type 'int
