revise code

This is a much simpler (better) version.

Author: fsaadatmand

chapter01/1-18.c

@@ -1,19 +1,17 @@
 /*
  * Exercise 1-18. Write a program to remove trailing blanks and tabs from each
  * line of input, and to delete entirely blank lines.
+ *
  * By Faisal Saadatmand
  */
 
 #include <stdio.h>
 
-#define MAXLINE       1000         /* maximum input line length */
-#define YES           1
-#define NO            0
+#define MAXLINE 1000         /* maximum input line length */
 
 /* functions */
-int  getLine(char [], int);
-int  delTrailingWS(char [], int);
-void delBlankLns(char [], int);
+int getLine(char [], int);
+int rightTrim(char [], int);
 
 /* getLine function: read a line into s, return length */
 int getLine(char s[], int lim)
@@ -33,59 +31,36 @@ int getLine(char s[], int lim)
 	return i;
 }
 
-/* delTrailingWS function: deletes trailing whitespaces and blank lines */
-int delTrailingWS(char s[], int len)
+int rightTrim(char s[], int len)
 {
-	int i, blankLine;
-	int newLength = len;      /* new length of line after whitespaces removal */
+	int nw = 0;
 
-	i         = 0;
-	blankLine = NO;
-
-	/* test for blanklines with witespaces */
-	while (s[i] == ' ' || s[i] == '\t' || s[i] == '\n')
-		++i;
-	if (i == len) {          /* remove whitespaces spaces form blank lines */
-		s[0] = '\n';
-		for (i = 1; s[i] != '\0'; ++i)
-			s[i] = '\0';
-		newLength -= i - 1;
-	}
-
-	if (s[0] == '\n') {
-		blankLine = YES;
+	if (s[--len] == '\n') {
+		s[len] = '\0';       /* remove newline character */
+		nw = 1;              /* set flag */
 	}
 
-	if (!blankLine) {          /* skip entirely blank lines */
-		while (s[len] == '\0' || s[len] == '\n' ||
-				s[len] == ' ' || s[len] == '\t') {
-			s[len] = '\0';
-			--len;
-		}
-		s[len + 1] = '\n';     /* insert newline char before null char */
-		newLength = len + 2;   /* plus 2 for the newline and null characters */
-	}
-	return newLength;
-}
+	while (--len >= 0  && (s[len] == ' ' || s[len] == '\t'))
+		s[len] = '\0';
+	++len;
 
+	if (nw)
+		s[len] = '\n';       /* add back the newline character */
 
-/* delBlankLns function: deletes entirely blank lines */
-void delBlankLns(char s[], int len)
-{
-	if (len == 1 && s[0] == '\n')
-		s[0] = '\0';
+	return ++len;
 }
 
 int main(void)
 {
 	int  len;                 /* current line length */
-	int  newLen;              /* modified line length */
 	char line[MAXLINE];       /* current input line */
 
 	while ((len = getLine(line, MAXLINE)) > 0) {
-		newLen = delTrailingWS(line, len);
-		delBlankLns(line, newLen);
+		len = rightTrim(line, len);
+		if (len == 1 && line[0] == '\n') /* delete if line is empty */
+			line[0] = '\0';
 		printf("%s", line);
 	}
+
 	return 0;
 }