C++ Program To Find Largest Number Among Three Numbers Using Nested Ifelse Statement

This article will guide you through creating a C++ program to identify the largest number among three given inputs. You will learn how to effectively use nested if...else statements to solve this common programming challenge.

Problem Statement

Identifying the largest number among a set of values is a fundamental operation in many computing contexts. In this scenario, the problem is to compare three distinct numerical inputs and accurately determine which one holds the maximum value. This task is crucial for applications requiring data sorting, filtering, or decision-making based on highest values.

Example

Consider three numbers: 10, 25, and 15. The program should be able to correctly identify 25 as the largest among them.

• Input: Number 1 = 10, Number 2 = 25, Number 3 = 15
• Output: The largest number is 25

Background & Knowledge Prerequisites

To understand this article, readers should have a basic understanding of:

• C++ Variables: How to declare and initialize variables of different data types (e.g., int or float).
• Input/Output Operations: Using std::cin to get input from the user and std::cout to display output.
• Conditional Statements (if...else): The basics of how if and else blocks execute code based on a condition.
• Logical Operators: Understanding && (AND) for combining conditions, though not strictly necessary for the nested approach, it's good to be aware.

Use Cases or Case Studies

Finding the largest number has numerous practical applications across various domains:

• Financial Analysis: Identifying the highest stock price, maximum profit, or largest expense in a given period.
• Gaming: Determining the highest score in a leaderboard or the strongest character attribute.
• Data Processing: Finding the peak value in a data stream, such as the highest temperature recorded or maximum sensor reading.
• Quality Control: Detecting the maximum deviation from a standard measurement in manufacturing.
• Resource Management: Allocating the largest available resource based on demand, like selecting the server with the most free memory.

Solution Approaches

This section details the approach using nested if...else statements to find the largest of three numbers.

Using Nested if...else Statements

This method involves a hierarchical structure of if...else conditions, where an outer if condition determines a primary comparison, and subsequent inner if...else statements resolve comparisons for the remaining numbers.

// Find Largest Number Among Three (Nested if-else)
#include <iostream>
using namespace std;

int main() {
    // Step 1: Declare three variables to store the numbers
    float num1, num2, num3;

    // Step 2: Prompt the user to enter three numbers
    cout << "Enter three numbers: ";
    cin >> num1 >> num2 >> num3;

    // Step 3: Use nested if-else to find the largest number
    if (num1 >= num2) {
        // num1 is greater than or equal to num2
        if (num1 >= num3) {
            // num1 is also greater than or equal to num3
            cout << "The largest number is: " << num1 << endl;
        } else {
            // num3 is greater than num1 (and num1 >= num2)
            cout << "The largest number is: " << num3 << endl;
        }
    } else {
        // num2 is greater than num1
        if (num2 >= num3) {
            // num2 is also greater than or equal to num3
            cout << "The largest number is: " << num2 << endl;
        } else {
            // num3 is greater than num2 (and num2 > num1)
            cout << "The largest number is: " << num3 << endl;
        }
    }

    return 0;
}

Run

Sample Output

Enter three numbers: 10 25 15
The largest number is: 25

Enter three numbers: 30 5 20
The largest number is: 30

Enter three numbers: 12.5 8.9 17.2
The largest number is: 17.2

Stepwise Explanation

1. Variable Declaration: Three floating-point variables (num1, num2, num3) are declared to accommodate numbers with decimal points.
2. User Input: The program prompts the user to enter three numbers, which are then stored in the declared variables using cin.
3. Outer if Condition (num1 >= num2):
   • It first checks if num1 is greater than or equal to num2.

1. Outer else Condition (if num1 < num2):
   • Since num2 is greater than num1, num2 is now the primary candidate. The program proceeds to an inner if...else block.

1. Output: The program prints the identified largest number to the console.

Conclusion

Using nested if...else statements provides a clear, although somewhat verbose, method for comparing three numbers and determining the largest. This approach breaks down the comparison into sequential, logical steps, ensuring that all possibilities are covered to correctly identify the maximum value. While other more compact methods exist, nested if...else is excellent for understanding fundamental control flow.

Summary

• Problem: Identify the largest among three numerical inputs.
• Approach: Utilizes nested if...else statements for sequential comparisons.
• Logic: An outer if...else compares two numbers, and an inner if...else resolves the comparison with the third.
• Readability: The nested structure makes the decision-making process explicit and easy to follow step-by-step.
• Application: Useful for basic value comparisons in various programming scenarios.