Check if string is just white space? [duplicate]

Possible Duplicate:
If string only contains spaces?

I do not want to change a string nor do I want to check if it contains white space. I want to check if the entire string is ONLY white space. What the best way to do that?

This will be the fastest way:

$str = '      ';
if (ctype_space($str)) {

}

Returns false on empty string because empty is not white-space. If you need to include an empty string, you can add || $str == '' This will still result in faster execution than regex or trim.

ctype_space

since trim returns a string with whitespace removed, use that to check

if (trim($str) == '')
{
 //string is only whitespace
}

if( trim($str) == "" )
    // the string is only whitespace

This should do the trick.

preg_match('/^\s*$/',$string)

change * to + if empty is not allowed