How to detect if string contains 1 uppercase letter in PHP

if (strtolower($url) != $url){
  //etc...

Some regular expression should be able to the work, you can use preg_match and [A-Z]

if(preg_match('/[A-Z]/', $domain)){
 // There is at least one upper
}

You can also try this

if (!ctype_lower($string)) {
    // there is at least une uppercase character
}

not sure if this is more efficient than the other two methods proposed.

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