Is there any special charactesr or not?

$myVariable1 = "[COLOR="#FF0000"][SIZE=5]([/SIZE][/COLOR]";
$myVariable2 = "a3bc123";
$myVariable3 = "ze3[COLOR="#FF0000"][SIZE=5]>[/SIZE][/COLOR]1fg";
$myVariable4 = "35[COLOR="#FF0000"][SIZE=5]%[/SIZE][/COLOR]cd[COLOR="#FF0000"][SIZE=5]:[/SIZE][/COLOR]";

In case of myVariable1, it has a special character only, i.e. (.

In case of myVariable2, it has no special characters.

In case of myVariable3, it has a special character, i.e. >.

In case of myVariable4, it has some special characters, i.e. % and :.

I like to make a condition about myVariables has any special characters, i.e. SIZE=5[/SIZE],$,>,>,:,;,,,%,/.

if ( $myVariables has any special characters )
{ echo "yes"; }
{ echo "no;} 

In case of myVariable1, myVariable3, and myVariable4, it says “yes”.
and In case of myVariable2, it says “no”.

How can I check myVariables has special characters or not?

Define ‘special characters’. ctype_alnum classifies a space as a special character.

Also your Locale setting will determine what ctype thinks constitutes a letter.

$myString = 'my text-1_2';
$myValid = array('-', '_',' ');

if(ctype_alnum(str_replace($myValid, '', $myString))) {
    echo '$myString consists of all English, digits, "-", or "_".';
echo '$myString has any of special characters.';

The code above is good, I think, when English is the only language.
But I like to make other languages, especially Korean language, are not recognized as special characters.