PHP Validate string characters are UK or US Keyboard characters

Question

What is the easiest or best way in PHP to validate true or false that a string only contains characters that can be typed using a standard US or UK keyboard with the keyboard language set to UK or US English?

To be a little more specific, I mean using a single key depression with or without using the shift key.

I think the characters are the following. 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz~`!@#$%^&*()_-+={[}]|\:;"'<,>.?/£ and Space

Answer 1

You can cover every ASCII character by [ -~] (i.e. range from space to tilde). Then just add £ too and there you go (you might need to add other characters as well, such as ± and §, but for that, have a look at the US and UK keyboard layouts).

Something like:

if(preg_match('#^[ -~£±§]*$#', $string)) {
    // valid
}

Answer 2

The following regular expression may be of use for you:

/^([a-zA-Z0-9!"#$%&'()*+,\-.\/:;<=>?@[\\\]^_`{|}~\t ])*$/m

Use this as:

$result = (bool)preg_match('/^([a-zA-Z0-9!"#$%&\'()*+,\-.\/:;<=>?@[\\\]^_`{|}~\t ])*$/m', $input);

Or create a reusable function from this code:

function testUsUkKeyboard($input) 
{
    return (bool)preg_match('/^([a-zA-Z0-9!"#$%&\'()*+,\-.\/:;<=>?@[\\\]^_`{|}~\t ])*$/m', $input);
}