In the last task, you might have noticed that we didn't consider the case when we print not valid age (for example, -1 or -6). Therefore, there should be a way to modify our code to predict such things.

If you want to add one more condition to check it, use else if statement:

if (condition#1) {
    // code here will be executed if the condition#1 is true
} else if (condition#2) {
    // code here will be executed if the condition#1 is false and 
condition#2 is true
} else {
    // code here will be executed if the condition#1 is false and 
condition#2 is false
}

So our modified code for the previous task will look as follows:

if (age < 0){
    cout << "The age you typed isn't valid. Try again, please.";
} else if (age >= 21) {
    cout << "You can buy alcohol.";
} else {
    cout << "You can't buy alcohol.";
}

The code initially checks if the age is valid. If the first statement is true the program prints a message if not - goes to the second condition. If the second condition is true and the user is over (or equal to) 21 years old the code prints a message, otherwise, both conditions are false and the customer is less than 21 and can’t buy alcohol.

You can add as many conditions using else if statement as you want.