a C program problem

[JoeNapoleon]

How are you.
in the C program,I tested it, but the result doesn't show the character '\b' for backspace, what's the problem?
# vim countwords.c
# gcc countwords.c
#./a.out

Thank you very much.

#include <stdio.h>

#define ESC_CHAR '\\'

int main(void)
{
  int c;

  while((c = getchar()) != EOF)
  {
    switch(c)
    {
      case '\b':
        putchar(ESC_CHAR);
        putchar('b');
        break;
      case '\t':
        putchar(ESC_CHAR);
        putchar('t');
        break;
      case ESC_CHAR:
        putchar(ESC_CHAR);
        putchar(ESC_CHAR);
        break;
      default:
        putchar(c);
        break;
    }
  }
  return 0;
}

[jpollard]

I think it will depend on your input.

Since you are reading stdin, which is buffered, the backspace (^H or \b) will be consumed by the terminal driver since it, by default, processes it automatically - Lookup the difference between "raw" mode and "cooked", though that may be a bit old nomenclature.

See the manpage on "stty", which will let you change the mode (though getting commands to work gets tricky afterwards - use Control N for the end of the line, and try not make any typos - you can't erase them...)