Check if a variable is a natural number

Question

I want to make a bid system on a website. That means users can post their bid (natural number). I want to make sure users don\'t try to post characters, decimal numbers, etc

Answer 1

ctype_digit does what you want:

Checks if all of the characters in the provided string, text, are numerical.

(Before PHP 5.1.0, this function returned TRUE when text was an empty string.)