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

This will return true if there are non-numbers in the string. It detects letters, spaces, tabs, new lines, whatever isn't numbers.

preg_match('#[^0-9]#',$variable)

Answer 2

Cast and compare:

function string_contain_number($val)
{
     return ($val + 0 == $val) ? true : false;
}

Answer 3

If you mean that you only want a value to contain digits then you can use ctype_digit().

Answer 4

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.