C Program to Check Whether a Number is Positive or Negative (Using Nested if...else)

#include <stdio.h>

int main() {

    double num;
    printf("Enter a number: ");
    scanf("%lf", &num);
    if (num <= 0.0) {
        if (num == 0.0)
            printf("You entered 0.");
        else
            printf("You entered a negative number.");
    } 
    else
        printf("You entered a positive number.");

    return 0;
}

Output 1

Enter a number: 12.3
You entered a positive number.

Output 2

Enter a number: 0
You entered 0.