Trying to return a 2D array

[Splam Bub]

Hello DaniWeb! I'm trying to return an array of strings from a function but I'm not sure how to do so. I've done the prerequisite Googling and have found people on this discussion board recommending to return char** which, it is said, can then be converted back into 2d array notation. It is this conversion to and from char** which has confused me and I have not been successful in clarifying this for myself, so my question is this:

How may I represent a 2D array in a fashion that can be returned as char**, and how would I re-convert this to 2D array representation once I have returned it?

Thank you for reading!

[Adak]

It's easier if you create the array in the calling function, then pass it into the called function as a parameter. Upon return from the called function, the array is still valid, and has the data you want in it.

You can do it the other way, but it's more work.

[Splam Bub]

This is a very good idea, and I hadn't thought of it. I did wonder why most of the library functions do it this way, and I now have an answer!

I shall leave this thread unsolved for now so that if I run into problems while trying to implement your suggestion, I won't clutter the forum up with a new topic. When I succeed, I shall mark as solved ;)

[Splam Bub]

Solved! Sorry for the delay.

Your solution worked very well, although I did have to do some research to understand why having "char param[][]" in the signature isn't legal in C. This is what I get for being green :)

Here's the test code I used, for those who come across this thread again via Google or otherwise:

#include <string.h>
#include <stdio.h>

static char arr[2][30] = {"hellotest1", "supbrotest2"};



int dothings(char sa[][30], char ma[][30])
{
	int i=0;
	while( strcpy(&ma[i][0], &sa[i][0])  &&  i++ < 2 );
	
	return 0;
}



int main()
{
	char mainarr[2][30];

	dothings(arr, mainarr);

	puts(&mainarr[0][0]);
	puts(&mainarr[1][0]);
	
	return 0;
}

Expected output:

hellotest1
supbrotest2