cout does not print char array

cout does not print char array

First of all, there is actually an output. It just outputs non-displayable characters

Displayable characters and non-displayable characters

Control characters are so-called non-printable characters

Solution

 char* index = data_in;
  std::cout << "start" << std::endl;
  while (*index != '\0') {
    std::cout << char(*index + '0');
    index++;
  }