Thread: [beginner] creating functions in a program

Well the first 2 "for" loops are just about identical, you I suppose that you can make a the contents of them a function (note that you can not use sizeof in another function, so you will have to pass that as a parameter). To put some strength in your code, you could check to see if fgets succeeded - And you can check to see if the input was too long by checking to see if '\n' is in the array. If this fails, you could return a -1 from a function and let your main try again.

You could move the last 3 printf's into 1.

You could check to see if the array select at the bottom is in the correct range before using it (i.e. what if I put in 42 by accident?)

Basically, I would work on making your code stronger.

Some rules of thumb I have:

1. Anything I'm going to do more than once should be its own function.

2. One function does one thing. If that "thing" can be logically broken down into smaller pieces, each piece should be a function, then the original function just calls them. For example, maybe I have an application that selects a collection of data, filters it, and then formats the filtered results for display. I would make each of these a function, even if I am not yet going to reuse any of them, because later when I decide I want a different option for a display - or a different collection of data to start from - I can leverage much of what I already have.

3. If a function is more than about 15-20 lines, it's probably something I should be decomposing into smaller pieces.

Some of this depends on context. On certain systems where performance is low and the overhead of a function call is high (e.g. some embedded systems), or where there were restrictions (e.g. low maximum number of stack levels) I would code differently.

Originally Posted by Spray

So I'm thinking about using functions in the program, but I'm not too sure where I'd do that in this example (maybe it's too small to do practically?)

Rewrite the part you want as if you had some functions already written. Next you can supply definitions for those functions and make sure the behaviour is the same. Here's one possibility

Code:

int main(void)
{
    char names[5][20];
    char phoneNumber[5][11];
    int select; 
     
    ask_data(names, 5, sizeof names[0], "Please enter names : \n\n");
    ask_data(phoneNumber, 5, sizeof phoneNumber[0], "Please enter phone numbers : ");
    ask_array(&select, 1, 9999, "Which array would you like? ");
     
    printf("name %i is   : %s\n", select, names[select]);
    printf("number %i is : %s\n", select, phoneNumber[select]);     
    printf("\n");
     
    return 0; 
}