Question

In C, how can I create a function which returns a string array? Or a multidimensional char array?

For example, I want to return an array char paths[20][20] created in a function.

My latest try is

char **GetEnv()
{
  int fd;
  char buf[1];
  char *paths[30];
  fd = open("filename" , O_RDONLY);

  int n=0;
  int c=0;
  int f=0;
  char tmp[64];

  while((ret = read(fd,buf,1))>0)
  {
    if(f==1)
    {
      while(buf[0]!=':')
      {
        tmp[c]=buf[0];
        c++;
      }
      strcpy(paths[n],tmp);
      n++;
      c=0;
    }
    if(buf[0] == '=')
      f=1;
  }
  close(fd);

  return **paths; //warning: return makes pointer from integer without a cast
  //return (char**)paths; warning: function returns address of local variable

}

I tried various ‘settings’ but each gives some kind of error.

I don’t know how C works

Answer 1

You can’t safely return a stack-allocated array (using the array[20][20] syntax).

You should create a dynamic array using malloc:

char **array = malloc(20 * sizeof(char *));
int i;
for(i=0; i != 20; ++i) {
    array[i] = malloc(20 * sizeof(char));
}

Then returning array works