#include <stdio.h>

int main (void) {
    float f = 124.0000;
    float n = 124.123000;

    if (f == (int) f) {
        printf("%.1f\n", f);
    } else {
        printf("%g\n", f);
    }

    if (n == (int) n) {
        printf("%.1f\n", n);
    } else {
        printf("%g\n", n);
    }
    return 0;
}

124.0
124.123