C Program to Check Whether a Number is Positive or Negative

In this example, you will learn to check whether a number (entered by the user) is negative or positive.
Positive and negative numbers in a number line

To understand this example, you should have the knowledge of the following C programming topics:

This program takes a number from the user and checks whether that number is either positive or negative or zero.


Check Positive or Negative Using 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;
}

You can also solve this problem using nested if else statement.


Check 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)
        printf("You entered a negative number.");
    else if (num > 0.0)
        printf("You entered a positive number.");
    else
        printf("You entered 0.");

    return 0;
}


Output 1

Enter a number: 12.3
You entered a positive number.

Output 2

Enter a number: 0
You entered 0.