3.15.1: Character operations.
C++
A 3-character string, passCode, is read from input. Replace each character in passCode that is not a digit with '$'. Otherwise, passCode is not changed.
Ex: If the input is q22, then the output is:
$22
confused on how to input the replacement character
A 3-character string, passCode, is read from input. Replace each character in passCode that is not a dig