空白（X'出）中间数字字母

Question

Is there a way to blank / x' out the middle (keep first and last two) digits / letters of a word or number ?

Example:

123456789 would be 12XXXXX89 or Iamaword = Iaxxxxrd

Answer 1

I wasn't sure if the uppercase or lowercase Xs were necessary, so the first line could be removed for simplicity:

$chr = ctype_digit($str) ? 'X' : 'x';  // big X for numbers, x for letters

$new_str = substr($str, 0, 2) . str_repeat($chr, strlen($str) - 4) . substr($str, -2);