FAQs in C: Check if a Number is Even or Odd

C Program to Check Whether a Number is Even or Odd

Here’s a C program to check whether a number is even or odd:

#include <stdio.h>

int main() {
    int number;

    // Step 2: Read an integer from the user
    printf("Enter an integer: ");
    scanf("%d", &number);

    // Step 3: Check if the number is even or odd
    if (number % 2 == 0) {
        // Step 4: Output if the number is even
        printf("%d is an even number.\n", number);
    } else {
        // Step 4: Output if the number is odd
        printf("%d is an odd number.\n", number);
    }

    // Step 5: End
    return 0;
}

Explanation:

Include Header: #include <stdio.h> is used to include the standard input-output library in C, which allows the use of printf and scanf.

Main Function: The main function is where the program starts execution.

Variable Declaration: An integer variable number is declared to store the user input.

Reading Input:

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

Conditional Check:

• if (number % 2 == 0) checks if the remainder when number is divided by 2 is zero. If true, the number is even.
• else handles the case when the remainder is not zero, meaning the number is odd.

Output:

• printf(“%d is an even number.\n”, number); prints the message that the number is even if the condition in the if statement is true.
• printf(“%d is an odd number.\n”, number); prints the message that the number is odd if the condition in the if statement is false.

Return Statement: return 0; indicates that the program ended successfully.

Algorithm:

Step 1: Start
Step 2: Input: Read an integer n from the user.

Step 3: Process:
        If n % 2 == 0 then:
             The number is even.
        Else:
             The number is odd.
             
Step 4: Output: Display whether the number is even or odd.
Step 5: End

Start

• This step indicates the beginning of the algorithm. It signifies the point at which the algorithm starts its execution.

Input: Read an integer n from the user.

• In this step, the algorithm waits for the user to input an integer value. This integer is stored in a variable n.

• This step is crucial because the algorithm needs a number to work with, and it can’t proceed without this input.

Process:

• This step involves the actual logic to determine if the number is even or odd.
• The algorithm uses the modulus operator % to check the remainder of the division of n by 2.
• Sub-step: If n % 2 == 0 then:
  • This sub-step checks if the remainder when n is divided by 2 is zero.
  • If n % 2 == 0 evaluates to true, it means n is divisible by 2 with no remainder, hence n is even.

Output: Display whether the number is even or odd.

• Based on the result of the check in step 3, the algorithm outputs a message indicating whether n is even or odd.

• If the condition in step 3 is true, it outputs that the number is even.

• If the condition in step 3 is false, it outputs that the number is odd.

End

• This step signifies the termination of the algorithm. It indicates that the algorithm has completed its execution.