pass string array out of function in c

Question

I have a function that I'm using to build a string array. Inside the function i can print the array no worries however the program returns from the called function, the array (arr) remains NULL. How do I get the data out of the array ?

Thanks.

main(){
  char **arr = NULL;
  funct(arr);
  printf("%s\n", arr[2];
}

funct(char **arr){
  arr = malloc(10*sizeof(char *));
  arr[1...n] = calloc(SIZE, sizeof(char));
  // Add data to array
}

Answer 1

I can see several problemens in your code:

1. in the line printf("%s\\n", arr[2]; you forgot a closing )
2. Your arr variable local to the main function is never initialized. In C, parameters are passed by value meaning that you are passing the NULL pointer to your function and inside this function, the local pointer arr is allocated but not the one of the main function.

The solution is to allocate the array in the main function and pass a pointer to the array and the size to the function that fills it:

main(){
  char **arr = malloc(10*sizeof(char *));
  funct(arr, 10);
  printf("%s\n", arr[2]);
}

funct(char **arr, int size){
  // Add data to array
  arr[0] = "first data";
  ....
  arr[size -1] = "last data";
}