ansi_c_pg31_ch01_ex18.c

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


#include <stdio.h>
#define MAXLINE 1000		/* maximum input line length */

int
get_line(char s[], int lim) {
	int             c, i;
	for (i = 0; i < lim - 1 && (c = getchar()) != EOF && c != '\n'; ++i)
		s[i] = c;
	if (c == '\n') {
		s[i] = c;
		++i;
	}
	s[i] = '\0';
	return i;
}

int
chomp(char* str) {
	int i,j;

	i  = 0;
	j = -1;


	/* handle empty string as a especial case */
	if (str[i] == '\0')
		return 0;

	while (str[i] != '\0') {
		if (str[i] != ' ' && str[i] != '\t' && str[i] != '\n') {
			j = i;
		}
		i++;
	}
	/*
	 * if the string is nothing but blanks,
	 * then terminate it
	 */
	if (j < 0 ) {
		str[0] = '\0';
		return 0;
	}

	/*
	 * if there is a gap, just insert '\n' before terminating the string
	 * otherwise, the string is already free of tail blanks
	 */

	if (i > j + 1) {
		str[j+1] = '\n';
		str[j+2] = '\0';
	}
	return j+1;
}

int
main()
{
	int   len;
	char   line[MAXLINE];
	/* current line length */
	/* maximum length seen so far */
	while ((len = get_line(line, MAXLINE)) > 0) {
		chomp(line);
		printf("%s",line);
	}
	return (0);
}