#include <stdio.h>

  #define MAXLEN 30

  void escape(char s[], char t[]);
  void unescape(char s[], char t[]);

  int main()
  {
      char input[MAXLEN] = "bla\tbla\nbla\n";
      char output[MAXLEN];

      printf("Original   = %s\n", input);
      escape(output, input);
      printf("Escaped    = %s\n", output);
      unescape(input, output);
      printf("Unescaped  = %s\n", input);
      printf("The End\n");

      return 0;
  }

  void escape(char s[], char t[])
  {
      int i, j;

      for (i = 0, j = 0; s[i]; i++, j++)
          switch (t[i]) {
          case '\t':
              s[j++] = ' ';
              s[j] = 't';
              break;
          case '\n':
              s[j++] = ' ';
              s[j] = 'n';
              break;
          default:
              s[j] = t[i];
              break;
          }
      s[j] = t[i];  // \0  !
  }

  void unescape(char s[], char t[])
  {
      int i, j;

      for (i = 0, j = 0; s[i]; i++, j++)
          switch (t[i]) {
          case ' ':
              switch (t[++i]) {
              case 't':
                  s[j] = '\t';
                  break;
              case 'n':
                  s[j] = '\n';
                  break;
              }
              break;
          default:
              s[j] = t[i];
              break;
          }
      s[j] = t[i];
  }