C verify input

[burningbannas]

Hello,
Need to make it so that if a RATIONAL number is entered it returns 1 and if a letter/nothing is entered it returns 0. Before, I used "int" and %d and the program worked perfectly for integers, but now I need it to also work with numbers that have decimals... I tried changing the %d to %f and int to double but it didn't work..
Thanks

#include <stdio.h>
int main(void)
{
double x1, y1
   printf("Enter point #1:\n");
    if (scanf("%f%f", &x1,&y1)==2)
    {
        return 1;
    }
    else
    {
        printf("Invalid Entry.\n");
		return 0;
}

[Aceix]

Thought %f was for float type.

Aceix.