Write a C++ program that takes three integers/numbers as input and outputs the largest of the three.

Input and Output Examples

1. Input: 5, 13, 2 Output: The largest number is 13.
2. Input: -1, -3, -2 Output: The largest number is -1.

Algorithm

1. Prompt the user to enter three integer numbers.
2. Compare the first number with the second and third numbers, if it is the largest number, print that number.
3. If not, check for the same with second and third number.
4. Print the largest number.

Here is the C++ code that follows the above algorithm to find the largest number among the three input values. 

#include <iostream>
using namespace std; 

int main() {
    int num1, num2, num3, largest;

    // Step 1: Input three numbers from the user
    cout << "Enter three numbers: ";
    cin >> num1 >> num2 >> num3;

    // Step 2 & 3: Compare the numbers and find the largest
    if (num1 >= num2 && num1 >= num3) {
        largest = num1;
    } else if (num2 >= num1 && num2 >= num3) {
        largest = num2;
    } else {
        largest = num3;
    }

    // Step 4: Output the largest number
    cout << "The largest number is " << largest << ".";

    return 0; 
}

Testing with Different Input Values

This program can handle any integers, whether positive, negative, or zero. Below are examples demonstrating its versatility:

Input and Output Examples for Modified Program:

1. Input: 100, 25, 100 Output: The largest number is 100.
2. Input: 0, 0, 0 Output: The largest number is 0.