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Finally there is the problem that the return type is "pointer to char", while you're attempting to return an array of arrays of pointers to char. Use something like this: char *testfunc () { char* arr = malloc (100); strcpy (arr,"xxxx"); return arr; } To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Not the answer you're looking for? That way you can allocate an object whose lifetime survives the end of the function. The following code also doesn't do what I want it to properly: I want to fill the array that the pointer parsed points to but this doesnt' happen in the code above. and when should I call delete[] on it. Can I use my Coinbase address to receive bitcoin? Unexpected uint64 behaviour 0xFFFF'FFFF'FFFF'FFFF - 1 = 0? Not the answer you're looking for? Thus, if you really want to stick to traditional arrays allocated dynamically, you can pass the size of the array as a reference parameter ("out-value") to a function like so: As you can see, a side-effect of manually allocating memory is that the client takes responsibility of it, and you have to manually delete it outside of the function where it was allocated. 1) The purpose of the function is to create and return an array of strings. c - How to initialise a 2d array using a void function? - Stack Overflow C++ Strings: Using char array and string object - Programiz Which ability is most related to insanity: Wisdom, Charisma, Constitution, or Intelligence? However the best practice is to either pass array to return as parameter or allocate array dynamically using malloc() function. If you create the array within the function like that, as a local variable (i.e. You'll need to use malloc to allocate the string. I've searched and found dozens of solutions to returning a character array from a function, but none of them works. Use dynamic allocation (the caller will have the responsibility to free the pointer after using it; make that clear in your documentation), Make the caller allocate the array and use it as a reference (my recommendation). Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey. @WanAfifiWanZain does the reply I put solve your question? I only have to add that you need to account for the terminating null character of. What's the function to find a city nearest to a given latitude? It is clear that inside function our array successfully got initialized, but something awful happened after returning it from function. How to insert an item into an array at a specific index (JavaScript), Sort array of objects by string property value. en.wikipedia.org/wiki/Return_value_optimization, How a top-ranked engineering school reimagined CS curriculum (Ep. Go https://nxtspace.blogspot.com/2018/09/return-array-of-string-and-taking-in-c.html Returning multi-dimensional array from function is similar as of returning single dimensional array. Asking for help, clarification, or responding to other answers. Returning a char* in C - Stack Overflow Also I find it useful to write a simple array of string implementation which has a minimal API for data manipulation. Why is processing a sorted array faster than processing an unsorted array? you need the return type to be char(*)[20]. That is simply ill-formed. If you want to return a single-dimension array from a function, you would have to declare a function returning a pointer as in the following example rev2023.5.1.43405. Connect and share knowledge within a single location that is structured and easy to search. But I personally prefer to pass array to return as argument and fill the resultant array inside function with processed result. Generic Doubly-Linked-Lists C implementation. @abligh It doesn't matter whether title and main question exactly match. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Move constructor called twice when move-constructing a std::function from a lambda that has by-value captures. Well, if you can change where you keep the array, then a minimal fix to your code is to put the array into main, and pass a reference to it into read, so that read can fill it. Very old versions of C did not even allow returning structs from functions, only scalar values (numerical types and pointers). String literals (stuff in quotes) are read-only objects of type array of char, stored in some sort of read-only memory (neither on stack or heap). It's not wrong. [duplicate], How a top-ranked engineering school reimagined CS curriculum (Ep. Find centralized, trusted content and collaborate around the technologies you use most. 1. The declaration of strcat() returns a pointer to char (char *). In C programming String is a 1-D array of characters and is defined as an array of characters. Function mycharheap() is leaking: you make your pointer point to a memory region of the length of one char allocated on the heap, and then you modify that pointer to point to a string literal which is stored in read-only memory. You can fill in pre-allocated memory (good), or allocate your own within the function and return it (bad). char* is just a pointer type you can use to pass addresses around. A minor scale definition: am I missing something? The behaviour of accessing memory pointed by a dangling pointer is undefined. Array is a data structure to store homogeneous collection of data. Just remember to free all the elements later (on the calling function). How can I write a function which returns array with repeating strings grouped together? 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. Be sure to free() the memory after you are done with it: A char array is returned by char*, but the function you wrote does not work because you are returning an automatic variable that disappears when the function exits. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, That does not work. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. I have previously created many functions that return character strings as char arrays (or at least pointers to them). How a top-ranked engineering school reimagined CS curriculum (Ep. This code works, but causes a warning : "Some string\n" is a string literal and will therefore exist for the lifetime of the program, so the following would be valid: Of course this is only useful if the function always returns the same string. Can my creature spell be countered if I cast a split second spell after it? There are two ways to return an array indirectly from a function. Further applying [0] on that character is ill-formed since there is no subscript operator for arguments char and int. Simple deform modifier is deforming my object. Array : Return a pointer to array from a function in C++? Passing negative parameters to a wolframscript. Can't seem to get a char array to leave a function and be usable in main. Which language's style guidelines should be used when writing code that is supposed to be called from another language? Hence, returning a memory location which is already released will point at no mans land. The main problem however is that since the memory is dynamically allocated, when you return a pointer to that memory, you only give the client half the information: the size of the array remains unknown. Why is char[] preferred over String for passwords? Counting and finding real solutions of an equation, Two MacBook Pro with same model number (A1286) but different year. He also rips off an arm to use as a sword. So far, I am able to read the correct values. How to Return a Local Array From a C++ Function? Basicly, this is what I want to do. You can't have an array as your return parameter in C++ The easiest way for us to help you is if you give us the original C++ function declaration, from there it's normally pretty easy. Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey, Output changes when I put my code into a function. How to Make a Black glass pass light through it? Hence it's called C-strings. Arrays in C are passed by reference, hence any changes made to array passed as argument persists after the function. If you want it as a return value, you should use dynamic memroy allocation, You should be aware of the fact that the array as filled above is not a string, so you can't for instance do this. 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. As others correctly said you should use dynamic memory allocation by malloc to store your array inside heap and return a pointer to its first element. How to return a string from a char function in C, Understanding pointers used for out-parameters in C/C++. Thanks for contributing an answer to Stack Overflow! Return char array from function - C++ Forum - cplusplus.com