Hi,
These are my worked examples. I am posting just in case some may want
to comment.
exercise1-17:
-------------------------
#include <stdio.h>
#define MAXLINE 1000 /* maximum length of line */
int lgetline(char line[], int maxline);
/* print lines longer than 80 characters */
int main() {
int len; /* current line length */
char line[MAXLINE]; /* current input line */
int j;
while ((len = lgetline(line, MAXLINE)) > 0) {
if (len >= 80) {
/* print if len is at least 80 characters */
for (j = 0; j < len && putchar(line[j]); ++j);
printf("\n");
}
}
return 0;
}
/* getine: read a line into s, return length */
int lgetline(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;
}
--------------------------
Exercise1-18
-------------------------
#include <stdio.h>
#include <string.h>
#define MAXLINE 1000 /* maximum length of line */
int lgetline(char line[], int maxline);
/* delete trailing spaces/tabs and delete empty lines */
int main() {
int len; /* current line length */
char line[MAXLINE]; /* current input line */
int j;
/* print if len > 0 */
while ((len = lgetline(line, MAXLINE)) > 0) {
int k = remove_trailing(line, len);
len = k;
for (j = 0; j <= len && putchar(line[j]); ++j);
printf("\nline length = %d", strlen(line));
printf("\n");
}
return 0;
}
/* getine: read a line into s, return length */
int lgetline(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 remove_trailing(char s[], int len)
{
int i = len - 1;
while (--i && (s[i] == '\t' || s[i] == ' ' || s[i] == '\n'));
s[i + 1] = '\n';
return i + 1;
}
------------------------
Exercise1-19:
------------------------
#include <stdio.h>
#define MAXLINE 1000 /* maximum length of line */
int lgetline(char line[], int maxline);
void reverse(char s[], int len);
/* reverse lines */
int main() {
int len; /* current line length */
char line[MAXLINE]; /* current input line */
int j;
/* print if len > 0 */
while ((len = lgetline(line, MAXLINE)) > 0) {
reverse(line, len);
for (j = 0; j < len && putchar(line[j]); ++j);
printf("\n");
}
return 0;
}
/* getine: read a line into s, return length */
int lgetline(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;
}
void reverse(char s[], int len)
{
/* Integer division is a truncating operation that discards
* the fractional part. This is what we want.
* Reason: if len is odd, the central character will always be
* in place. If not swapping half the string will do the trick.
*/
len = len - 1;
int i, j = len/2;
char ch;
for (i = 0; i < j; ++i) {
ch = s[i];
s[i] = s[len - i - 1];
s[len - i - 1] = ch;
}
}
-------------------------------------
_______________________________________________
Dng mailing list
Dng@lists.dyne.org
https://mailinglists.dyne.org/cgi-bin/mailman/listinfo/dng
