C Program to Find the Largest of Three Numbers

Introduction

Finding the largest of three numbers is a common programming problem that helps in understanding the use of conditional statements. This guide will show you how to write a C program to determine the largest of three numbers provided by the user.

Problem Statement

Create a C program that:

• Takes three numbers as input from the user.
• Compares the numbers to find the largest one.
• Displays the largest number.

Example:

• Input: a = 5, b = 10, c = 7
• Output: The largest number is 10

Solution Steps

1. Include the Standard Input-Output Library: Use #include <stdio.h> to include the standard input-output library, which is necessary for using printf and scanf functions.
2. Write the Main Function: Define the main function, which is the entry point of every C program.
3. Declare Variables: Declare variables to store the three numbers.
4. Input the Numbers: Use scanf to take input from the user for the three numbers.
5. Compare the Numbers Using Conditional Statements: Use if-else statements to compare the three numbers and determine the largest one.
6. Display the Largest Number: Use printf to display the largest number.

C Program

#include <stdio.h>

/**
 * C Program to Find the Largest of Three Numbers
 * Author: https://www.javaguides.net/
 */
int main() {
    // Step 1: Declare variables to hold the three numbers
    int a, b, c;

    // Step 2: Prompt the user to enter the first number
    printf("Enter the first number (a): ");
    scanf("%d", &a);

    // Step 3: Prompt the user to enter the second number
    printf("Enter the second number (b): ");
    scanf("%d", &b);

    // Step 4: Prompt the user to enter the third number
    printf("Enter the third number (c): ");
    scanf("%d", &c);

    // Step 5: Compare the numbers using if-else statements
    if (a >= b && a >= c) {
        // If a is greater than or equal to both b and c, then a is the largest
        printf("The largest number is %d\n", a);
    } else if (b >= a && b >= c) {
        // If b is greater than or equal to both a and c, then b is the largest
        printf("The largest number is %d\n", b);
    } else {
        // If neither a nor b is the largest, then c must be the largest
        printf("The largest number is %d\n", c);
    }

    return 0;  // Step 6: Return 0 to indicate successful execution
}

Explanation

Step 1: Declare Variables

• Variables a, b, and c are declared as integers to hold the three numbers entered by the user.

Step 2: Input the First Number

• The program prompts the user to enter the first number using printf. The scanf function then reads the input and stores it in the variable a.

Step 3: Input the Second Number

• Similarly, the program prompts the user to enter the second number, which is stored in the variable b.

Step 4: Input the Third Number

• The program prompts the user to enter the third number, which is stored in the variable c.

Step 5: Compare the Numbers Using Conditional Statements

• The program uses if-else statements to compare the three numbers:
  • If a is greater than or equal to both b and c, then a is the largest.
  • If b is greater than or equal to both a and c, then b is the largest.
  • Otherwise, c is the largest.

Step 6: Display the Largest Number

• The program displays the largest number using the printf function.

Step 7: Return 0

• The return 0; statement indicates that the program executed successfully.

Output Example

Example:

Enter the first number (a): 5
Enter the second number (b): 10
Enter the third number (c): 7
The largest number is 10

Conclusion

This C program demonstrates how to find the largest of three numbers using conditional statements. It covers basic concepts such as variable declaration, taking user input, and using if-else statements, making it a useful example for beginners learning C programming.