Mere seconds before the Earth is to be demolished by an alien construction crew, journeyman Arthur Dent is swept off the planet by his friend Ford Prefect, a researcher penning a new edition of “The Hitchhiker’s Guide to the 



Each of the expressions can be empty or contain multiple expressions separated by commas. In expr2, all expressions separated by a comma are evaluated but the result is taken from the last part. expr2 being empty means the loop should be run indefinitely (PHP implicitly considers it as TRUE, like C). This may not be as useless as you might think, since often you’d want to end the loop using a conditional break statement instead of using the for truth expression.