Exercise 1-18 (continued)

Exercise 1-18  Write a program to remove trailing blanks and tabs from each line of input, and to delete entirely blank lines.

This program can buffer up to a certain number of blank characters, and spills only one character at a time when the buffer is full.

#include <stdio.h>

#define BUFFERSIZE 100

int bufpos = 0;

char buffer[BUFFERSIZE];

void clear_buffer(void)

{

  bufpos = 0;

}

void flush(void)

{

  int i;

  for (i = 0; i < bufpos; ++i)

    putchar(buffer[i]);

  clear_buffer();

}

void push(char c)

{

  if (bufpos<BUFFERSIZE)

    buffer[bufpos++] = c;

  else

  {

    int i;

    putchar(buffer[0]);

    for (i=1; i<BUFFERSIZE; ++i)

      buffer[i-1] = buffer[i];

    buffer[BUFFERSIZE-1] = c;

  }

}

void display(char c)

{

  flush();

  putchar(c);

}

void strip(char c)

{

  switch(c)

  {

  case ' ':

  case '\t':

    push(c);

    break;

  case '\n':

    clear_buffer();

    putchar(c);

    break;

  default:

    display(c);

    break;

  }

}

int main(void)

{

  int c;

  int newline = 1;

  while (c=getchar(), c!=EOF)

  {

    if (!newline || c!='\n')

    {

      newline = 0;

      strip(c);

    }

    if (c=='\n')

      newline = 1;

  }

  return 0;

}