C Programs

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Decision Making Programs in C

Find the largest of three numbers

Introduction

Finding the largest among three numbers is a classic decision-making problem.
We can solve it using:

• if-else statements
• Or using nested ifs

The logic:

1. If num1 >= num2 and num1 >= num3 → num1 is largest
2. Else if num2 >= num1 and num2 >= num3 → num2 is largest
3. Else → num3 is largest

C Program: Find the largest of three numbers

#include <stdio.h>
 
int main() {
    int num1, num2, num3;
 
    // Input three numbers
    printf("Enter first number: ");
    scanf("%d", &num1);
    printf("Enter second number: ");
    scanf("%d", &num2);
    printf("Enter third number: ");
    scanf("%d", &num3);
 
    // Compare numbers
    if (num1 >= num2 && num1 >= num3) {
        printf("%d is the largest number.\n", num1);
    } else if (num2 >= num1 && num2 >= num3) {
        printf("%d is the largest number.\n", num2);
    } else {
        printf("%d is the largest number.\n", num3);
    }
 
    return 0;
}

 
OUTPUT 1 :
Enter first number: 10
Enter second number: 25
Enter third number: 20
25 is the largest number.

OUTPUT 2 :
Enter first number: 50
Enter second number: 50
Enter third number: 40
50 is the largest number.

OUTPUT 3 :

Enter first number: 30
Enter second number: 30
Enter third number: 30
30 is the largest number.

Explanation

1. User inputs three numbers.
2. Program uses logical AND (&&) to check:
   • num1 >= num2 && num1 >= num3 → num1 is largest
   • num2 >= num1 && num2 >= num3 → num2 is largest
   • Otherwise → num3 is largest
3. Handles equal numbers