[php] trouver le ième caractère ds un string

function searchPos ( $source, $occurence, $number ){
	
	$found 	= FALSE;
	$curs 	= 0;
	
	do{
		
		// --- try to retrieve index of char to found : (FALSE if not found)
		$currentPos = strpos($source,$occurence);
		
		// --- test return value && current counter
		if ( $currentPos != FALSE ){
			// --- Increase counter
			$curs++;
			// --- Test if current counter equals to number of the occurent to retrieve
			if ( $curs == $number )
				$found = TRUE;
		}
		
	}while ( $found != FALSE && $currentPos != FALSE );
	// --- Loop on source string to retrieve the occurence
	
	// --- Test if occurence had been found and return position if OK
	if ( $found == TRUE )
		return $currentPos;
	else
		// --- Return default not found value '-1'
		return -1;
	
}