The if expression also allows for multiple expressions to be evaluated at once. The general form of this statement in Erlang is shown in the following program −
if condition1 -> statement#1; condition2 -> statement#2; conditionN -> statement#N; true -> defaultstatement end.
In Erlang, the condition is an expression which evaluates to either true or false. If the condition is true, then statement#1 will be executed. Else the next condition is evaluated and so on and so forth. If nothing evaluates to true then the defaultstatement is evaluated.
The following image is a general diagrammatic representation of the above given statement.
The following program is an example of a simple if expression in Erlang −
-module(helloworld). -export([start/0]). start() -> A = 5, B = 6, if A == B -> io:fwrite("A is equal to B"); A < B -> io:fwrite("A is less than B"); true -> io:fwrite("False") end.
The following key things need to be noted about the above program −
The expression being used here is the comparison between the variables A and B.
The -> operator needs to follow the expression.
The ; needs to follow statement#1.
The -> operator needs to follow the true expression
The statement â€˜endâ€™ needs to there to signify the end of the if block.
The output of the above program will be −
A is less than B