In C, an Odd or Even program determines whether a given integer is odd or even by checking the remainder when the number is divided by 2. If the remainder is zero, the number is even; otherwise, it is odd.

Steps for the Odd or Even Program:

1. Include Header Files: Include the stdio.h library for input/output functions.
2. Declare Variables: Use a variable to store the number that will be input by the user.
3. Take Input: Ask the user to enter an integer.
4. Check the Number: Use the modulus operator (%) to check if the number is divisible by 2.
5. Display Output: Print whether the number is odd or even.

Program:

#include <stdio.h>

int main() {
    int num;  // Declare a variable to store the integer input by the user

    // Ask the user to enter an integer
    printf("Enter an integer: ");
    scanf("%d", &num);  // Read the input from the user

    // Check if the number is even or odd using the modulus operator
    if (num % 2 == 0) {
        // If the remainder is 0, it is an even number
        printf("%d is even.\n", num);
    } else {
        // If the remainder is not 0, it is an odd number
        printf("%d is odd.\n", num);
    }

    return 0;
}

Explanation:

1. Variables:

   • int num: This variable stores the integer entered by the user.

2. Input:

   • printf("Enter an integer: "); prompts the user to enter a number.
   • scanf("%d", &num); reads the input number from the user and stores it in the variable num.

3. Checking Odd or Even:

   • The condition if (num % 2 == 0) checks whether the remainder is 0 when the number is divided by 2 using the modulus operator (%).
     • If num % 2 == 0, the number is even, and it prints the message num is even.
     • If num % 2 != 0, the number is odd, and it prints the message num is odd.

4. Output:

   • Depending on the input and the condition, the program will display whether the number is even or odd.

Sample Output:

Example 1:

Enter an integer: 10
10 is even.

Example 2:

Enter an integer: 7
7 is odd.

Key Points:

• The modulus operator (%) is crucial for checking divisibility. If the remainder is zero when dividing by 2, the number is even; otherwise, it's odd.
• %d is the format specifier used to read and print integers.
• Conditions: The if-else structure helps determine the result based on the input number.

This program provides a simple way to classify numbers as odd or even using basic input/output and conditional logic in C.