CODEWITHSUNDEEP
c++escapingnewlinestdout
nluka
nluka

Reputation: 151

Escaping newline character when writing to stdout in C++

I have a string in my program containing a newline character:

char const *str = "Hello\nWorld";

Normally when printing such a string to stdout the \n creates a new line, so the output is:

Hello
World

But I would like to print the string to stdout with the newline character escaped, so the output looks like:

Hello\nWorld

How can I do this without modifying the string literal?

Upvotes: 2

Views: 1351

Answers (1)

nluka
nluka

Reputation: 151

The solution I opted for (thanks @RemyLebeau) is to create a copy of the string and escape the desired escape sequences ("\n" becomes "\\n").

Here is the function which does this escaping:

void escape_escape_sequences(std::string &str) {
  std::pair<char, char> const sequences[] {
    { '\a', 'a' },
    { '\b', 'b' },
    { '\f', 'f' },
    { '\n', 'n' },
    { '\r', 'r' },
    { '\t', 't' },
    { '\v', 'v' },
  };

  for (size_t i = 0; i < str.length(); ++i) {
    char *const c = str.data() + i;

    for (auto const seq : sequences) {
      if (*c == seq.first) {
        *c = seq.second;
        str.insert(i, "\\");
        ++i; // to account for inserted "\\"
        break;
      }
    }
  }
}

Upvotes: 2

Related Questions