tcpl_ex-1-21.c

tcpl_ex-1-21.c

/*
 * Exercise 1-21. Write a program  entab that replaces strings of blanks by the minimum 
 * number of tabs and blanks to achieve the same spacing. Use the same tab stops as for detab. 
 * When either a tab or a single blank would suffice to reach a tab stop, which should be given 
 * preference?  
 */

#include <stdio.h>

#define TABINC 8

int main(void) {
	int c, i, j;
	i = 0;					/* position 		*/
	j = 0; 					/* the space count 	*/
	while (EOF != (c = getchar())) {
		if (' ' == c) {
			j++;
			if (0 == (i + j)  % TABINC) {
				putchar('\t');
				i = i + j;
				j = 0;
			}

		} else {
			while (j > 0) {
				putchar(' ');
				i++;
				j--;
			}
			putchar(c);
			if ('\t' == c)
				i += (TABINC - (i % TABINC));
			else if ('\n' == c)
				i = 0;
			else
				i++;
		}
	}
	while (j > 0) {
		putchar(' ');
		i++;
		j--;
	}
	return 0;
}