how to check if PHP variable contains non-numbers?

Question

I just want to know the method to check a PHP variable for any non-numbers and if it also detects spaces between characters? Need to make sure nothing weird gets put into my for

Answer 1

You can use is_numeric() :

if ( is_numeric($_POST['foo']) ) {
    $foo = $_POST['foo'];
} else {
    // Error
}

This will check that the value is numerical, so it may contain something else than digits:

12
-12
12.1

But this will ensure that the value is a valid number.