ansi_c_pg34_ch01_ex20.c

/*
 * Exercise 1-20.
 * Write a program detab that replaces tabs in the input with the proper number
 * of blanks to space to the next tab stop. Assume a fixed set of tab stops, say
 * every n columns. Should n be a variable or a symbolic parameter?
 */

#include <stdio.h>


#define	TABSSTOP	8

int
main() {
	int c;
	int offset = 0;
	int spaces;

	while ((c = getchar()) != EOF) {
		if (c == '\t') {

			spaces = TABSSTOP  - (offset%TABSSTOP);
			offset += spaces;

			while (spaces--)
				putchar(' ');

		} else {
			if (c == '\n')
				offset = -1;
			offset++;
			putchar(c);

		}
	}
	return (0);
}