if - else - elseif

An if statement will execute the its following code block if the expression evaluates to true.

An else statement following an if statement can execute its code block if the same expression is `false``.

if (<condition>) {
    ...
    <code block for 'true'>
    ...
} else {
    ...
}

An elseif statement allows the specification of another expression, to execute another code block, should the first expression evaluate to false.

Example:

if (s == 5) {
    printf("s is equal to 5")
} elseif (s < 10) {
    printf("s is less than 10 (and is not 5)")
} else {
    printf("s is greater or equal to 10")
}