Reject empty/blank user input

Question

For pset1 I want to reject an empty user input, so that when the user presses 'enter', either the Mario code runs or it gives the user an error message.

Pseudo code:

1. printf ('message to input 1-23');

2. scansf ('%i', &height);

3. if (input <= 23 && input > 0)

{ ... a do/while (with 2 nested for) runs mario if input is 1-23. }

1. else

{ printf ("prints error message if input isn't 1-23");}

This rejects numbers outside the range and all characters, but not empty spaces. I reckon there's an elegant solution to this (can fgets work? How?), but advice would be helpful at this point.

Question: How do I reject an empty user input?

Answer 1

Use GetInt() from the cs50 library!

GetInt(), as its name suggests, waits for an int input from the user and returns it.

You may use like that:

#include <cs50.h>
#include <stdio.h>

int main(void)
{
    // prompt the user for an int
    printf("Please give me an int:");
    int i = GetInt();

    printf("Thanks for the %d", i);
}