For the "What you want:" part, Yossarian was faster than me. c++ - Returning const char* array from function - Stack Overflow In this chapter we'll study three workarounds, three ways to implement a function which attempts to return a string (that is, an array of char ) or an array of some other type. Did the drapes in old theatres actually say "ASBESTOS" on them? But "out-values" are a bad style really, especially in API's. 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. Why should I use a pointer rather than the object itself? Canadian of Polish descent travel to Poland with Canadian passport, Extracting arguments from a list of function calls. c - How to initialise a 2d array using a void function? - Stack Overflow Not the answer you're looking for? Whenever you pass an array to a function or declare it as a function parameter, it "decays" into a pointer to its first element. Why did US v. Assange skip the court of appeal? Returning objects allocated in the automatic storage (also known as "stack objects") from a function is undefined behavior. To learn more, see our tips on writing great answers. It is clear that inside function our array successfully got initialized, but something awful happened after returning it from function. What I expected it will return the Halloworld when i run it. Arrays are equally important as functions. Is my only choice to use pointers and void the function? Go https://nxtspace.blogspot.com/2018/09/return-array-of-string-and-taking-in-c.html If you are not going to change the chars pointed by the returnValue pointer ever in your programme, you can make it as simple as: This function creates allocates a memory block, fills it with the following: And then returns the address off the first element 't'. Just that using it after the function can cause undefined behaviour because functions called after this function could have overwritten the contents of the memory location( in the stack ). By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Is there a way to use pointers correctly instead of having to change my array and add struct types? If #1 is true, you need several malloc calls to make this work (It can really be done with only two, but for purposes of simplicity, I'll use several). Why is it shorter than a normal address? Short story about swapping bodies as a job; the person who hires the main character misuses his body. I had decay in the draft but then saw the pointer and removed it. He also rips off an arm to use as a sword. It's that you are reserving memory via malloc, but. Reason: It's of course better to use a proper dynamic array facility such as a std::vector, but that seems to not be the point of the exercise. "Signpost" puzzle from Tatham's collection, A boy can regenerate, so demons eat him for years. Hence it's called C-strings. The first left over 0x00 will act as a null terminator when passed to printf(). This is one of its many quirks, you just have to live with it. I appreciate but I think people need to understand with example not by word that's why I gave this link, and if you did not like, it's Ok. @SimonF. Function to read a file and return a double array in C Code Why is reading lines from stdin much slower in C++ than Python? So far, I am able to read the correct values. As noted in the comment section: remember to free the memory from the caller. Why is processing a sorted array faster than processing an unsorted array? ), it would look something more like this instead: Not so nice, is it? A normal char[10] (or any other array) can't be returned from a function. Create a pointer to two-dimensional array. 8.3.5[dcl.fct]/6: Functions shall not have a return type of type array or function[.] This is why we need to use const char*: const char* myName() { return "Flavio"; } Here's an example working program: Simple deform modifier is deforming my object. How to return a string from a function, while the string is in an array. because the "%s" expects a matching string to be passed, and in c an array is not a string unless it's last character is '\0', so for a 2 character string you need to allocate space for 3 characters and set the last one to '\0'. Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey. This works, but returned the buffer (or "array" if you want) wont be modifyable. @Someprogrammerdude Which happily loses the size information. You should not return the address of a local variable from a function as its memory address can be overwritten as soon as the function exits. The destructor of TiXmlDocument will destroy the owned memory, and the pointers in the array xmlread will be dangling after the function has returned. a NULL) at the end. The "above answer" doesn't invalidate it in any way. Thanks for contributing an answer to Stack Overflow! Why does setupterm terminate the program? A minor scale definition: am I missing something? I don't think I said that returning the said pair is strictly related to dynamic memory allocation, I simply addressed the concerns in this exact post. I NEED to end up with a char array rather than a string type purely because the char array is used to contain a pump port name ie "COM7" and is used as an argument in createfile() function to open the port to writting (actually a char pointer) this function does not accept string types. As you're using C++ you could use std::string. Not the answer you're looking for? In C programming, the collection of characters is stored in the form of arrays. Has the cause of a rocket failure ever been mis-identified, such that another launch failed due to the same problem? en.wikipedia.org/wiki/Return_value_optimization, How a top-ranked engineering school reimagined CS curriculum (Ep. 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. Array : In C++, I want to return an array of objects from a function Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Pass arrays to a function in C - Programiz Has the Melford Hall manuscript poem "Whoso terms love a fire" been attributed to any poetDonne, Roe, or other? The marked dupe has an accepted (and highly upvoted) answer, that explains the problem (exactly the same the OP asks for) in depth. I'll update my answer for you. (after 2,5 years ;) ) - Patryk Feb 1, 2016 at 23:09 It's the type for a pointer to a character or character sequence. How to force Unity Editor/TestRunner to run at full speed when in background? If the string length goes beyond the specified length, just its first 4 characters will be stored. Connect and share knowledge within a single location that is structured and easy to search. I guess there are other errors in the code and memory leaks, please let me know if any. Generic Doubly-Linked-Lists C implementation. NULL-terminated character arrays) from unmanaged code to managed code. 1) Allocate your array on the heap using malloc(), and return a pointer to it. Making statements based on opinion; back them up with references or personal experience. Two MacBook Pro with same model number (A1286) but different year, A boy can regenerate, so demons eat him for years. 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 ran your cod eand it's giving me, Returning const char* array from function, How a top-ranked engineering school reimagined CS curriculum (Ep. Why is char[] preferred over String for passwords? If you create the array within the function like that, as a local variable (i.e. In C++17 and beyond, RVO will be guaranteed by the language. How to initialize all members of an array to the same value? cout<<ptr [0] [0]<<endl; This cannot possibly work. What positional accuracy (ie, arc seconds) is necessary to view Saturn, Uranus, beyond? Asking for help, clarification, or responding to other answers. What are the advantages of running a power tool on 240 V vs 120 V? If he wants to do it the C++ way, OP should be using, Not that you should do that in C either. Take a look at: Please also pass the capacity as argument, it's too fragile this way. You can return a pointer for the array from a function, however you can't return pointers to local arrays, the reference will be lost. Use std::string. When a gnoll vampire assumes its hyena form, do its HP change? Let us write a program to initialize and return an array from function using pointer. var prevPostLink = "/2017/10/multi-dimensional-array-c-declare-initialize-access.html"; Does a password policy with a restriction of repeated characters increase security? To overcome this you can either allocate array dynamically using malloc() function. The cause of your compiler error is simple, but not the answer to what you really want to do. MIP Model with relaxed integer constraints takes longer to solve than normal model, why? Simple deform modifier is deforming my object, Effect of a "bad grade" in grad school applications. 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. The declaration of strcat() returns a pointer to char (char *). Connect and share knowledge within a single location that is structured and easy to search. 1) The purpose of the function is to create and return an array of strings. With move semantics returning potentially huge movable data is fine. That thing on the stack is just a pointer variable and you return the value of the pointer (the address it stores) by value. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. So, you're leaking memory. Using an Ohm Meter to test for bonding of a subpanel, Passing negative parameters to a wolframscript, Generic Doubly-Linked-Lists C implementation. get a proper answer.