Check if variable is a number and positive integer in PHP?

Question

For example, say:

How do I check if variable

Answer 1

To check if a string input is a positive integer, i always use the function ctype_digit. This is much easier to understand and faster than a regular expression.

if (isset($_GET['p']) && ctype_digit($_GET['p']))
{
  // the get input contains a positive number and is safe
}