1 - Détecter efficacement UTF-8
function detectUTF8($string)
{
return preg_match('%(?:
[xC2-xDF][x80-xBF] # non-overlong 2-byte
|xE0[xA0-xBF][x80-xBF] # excluding overlongs
|[xE1-xECxEExEF][x80-xBF]{2} # straight 3-byte
|xED[x80-x9F][x80-xBF] # excluding surrogates
|xF0[x90-xBF][x80-xBF]{2} # planes 1-3
|[xF1-xF3][x80-xBF]{3} # planes 4-15
|xF4[x80-x8F][x80-xBF]{2} # plane 16
)+%xs',
$string);
}