6.2.1: Conditional Execution - If-Else

The if-else Statement

There is also an if statement that has 2 parts to it. The statements that execute when the condition is TRUE, and the statements that execute when the statements is FALSE. The syntax for the if-else control structure:

// C++ program to illustrate if-else statement 
#include<iostream> 
using namespace std; 

int main() 
{ 
        int myNum = 20; 

        if (myNum < 15) 
            cout << "myNum is smaller than 15" << endl;
        else
            cout << "myNum is greater than 15" << endl;
            
    return 0;     
} 

Notice that we do NOT have the curly braces. This is allowed since we only have a single statement in the if portion and the else portion. You MAY include the brackets if you want to.

// C++ program to illustrate if-else statement 
#include<iostream> 
using namespace std; 

int main() 
{ 
        int myNum = 20; 

        if (myNum < 15) 
        {
            cout << "myNum is smaller than 15" << endl;
            myNum = 99;
        }
        else
            cout << "myNum is greater than 15" << endl;
            
    return 0;     
} 

This again is valid, you only need the curly brackets if you want to include more than a single statement in your block of code. In this case if you left out the brackets you would get an error on the else statement.

Adapted from:
"If Then Else" by Kenneth Busbee, Download for free at http://cnx.org/contents/303800f3-07f...93e8948c5@22.2 is licensed under CC BY 4.0 
"Decision Making in C / C++ (if , if..else, Nested if, if-else-if )" by Harsh Agarwal, Geeks for Geeks is licensed under CC BY-SA 4.0