C++ program to Find the largest among three numbers

In this program, we will learn to find the largest number among the three numbers given by the user.

To understand this, you should have knowledge of-

• Variables
• How to take user input
• if…else if…else conditional statement
• && operator
• Ternary operator

We will do this program by 2 methods-

• Using if…else if…else statement
• Using the ternary operator

Program 1(Using an if…else if…else statement)

#include<iostream>
using namespace std;
int main() 
{
    int x , y, z, res;
    cout<<"Enter first number - ";
    cin>>x;
    cout<<"Enter second number - ";
    cin>>y;
    cout<<"Enter third number ";
    cin>>z;
    if(x>=y && x>=z)
    {
        res = x;
    }
    else if(y>=x && y>=z)
    {
        res = y;
    }
    else
    {
        res = z;
    }
    cout<<"The largest number is: "<<res;
    return 0;
}

Output:

Enter first number: 4
Enter second number: 7
Enter third number: 2
The largest number is: 7

Explanation:

• When this program runs, the user will see three subsequent messages to enter three numbers. Those numbers will be stored in the variables named x, y, and z respectively.
• Then, we made an if…else if…else tree to find out the largest number. In the if statement, we have written two conditions separated by the && operator. The && operator returns true if both the conditions are true, or it returns false otherwise. What this means is, if both the conditions x >= y and x >= z are true, it will return true, and x will be considered the largest number.
• The same is with the else if statement. If both the conditions written inside it are true, y will be considered the largest number.
• If both if and else if statements returned false, the else statement will be evaluated, and z will be considered as the largest number.

Program 2(Using the ternary operator)

Note: The ternary operator is also called as a conditional operator.

Syntax: (Expression 1 ) ? Expression2 : Expression3

In this, the operator returns one of the two values. Here if Expression 1 is evaluated to true then Expression 2 is evaluated and its result is returned but if expression 1 is false, then Expression 3 will be evaluated and its result will be returned.

#include<iostream>
using namespace std;
int main()
 {
    int x, y, z, res;
    cout<<"Enter first number: ";
    cin>>x;
    cout<<"Enter second number: ";
    cin>>y;
    cout<<"Enter third number: ";
    cin>>z;
    res = ( x > y && x > z ) ? x : (y > z ? y : z);

    cout<<"The largest number is: "<<res<<endl;

    return 0;
}

Output:

Enter first number: 4
Enter second number: 7
Enter third number: 2
The largest number is: 7