6.4.15 The if Expression

An if expression has the following form:

     if condition1 then
       expression1
     elseif condition2 then
       expression2
     else
       expression3
     end if

The elseif part may be repeated unrestrictedly (including zero times).

First, condition1 is evaluated. If it is satisfied, the expression expression1 is evaluated and yields the value of the if expression.

If condition1 is not satisfied, each condition following an elseif keyword is evaluated in turn, until a condition is found that is satisfied. The expression that follows this condition will be evaluated and yields the value of the if expression.

If the if condition and elseif conditions all fail, the expression expression3 will be evaluated and yields the value of the if expression.

The if after the end may be omitted.