Question

I got a char **function which returns obviously an Array of chars…. the problem is that I don’t know how many strings are filled in the array …. char *data[size_of_data]; has been set at the first, but the function may not need all the array fields….

presume I got int size_of_data = 100 , but it just got 15 Strings …. if I want to break after the 15th String, which condition do I need in C … I got the data already in a char ** field and tried sth like….

 while(strcmp(data[i],'\0'))
{
    msg_send (session, para[0],data[i]);
    printf("------> %s \n",data[i]);
}   

Answer 1

One thing you can do is to also provide the size of the array as an out parameter. Your function signature would look like this

char ** function(size_t * num_strings); //num_strings is an out parameter

Then you do something like so

size_t nstrings = 0;
char **strings = function(&nstrings);
size_t i = 0;
while (i < nstrings) {
    //do stuff
}

There’s an advantage to knowing the size, instead of just iterating until you hit a null pointer. Say you prepared an array of 100 char*. What if you use them all? There’s no null pointer, and you’ll have overrun your buffer. Of course, you could add an extra pointer at the end as a delimiter, but personally I like having the size.