- substr: documentation ( source)
- var_dump: documentation ( source)
- mb_strlen: documentation ( source)
- str_pad: documentation ( source)
<?php
$value = 'Cession de Fonds de commerce / activité';
$length = 100;
$diff = strlen($value) - mb_strlen($value, 'UTF-8');
$padChar='-';
$padType = PAD_RIGHT;
$value = substr(str_pad($value, $length + $diff, $padChar, $padType), 0, $length + $diff);
var_dump($value, strlen($value));