In exercise 1-16 in The C Programming Language (K & R) it asks for us to: revise the main routine of the longest-line program so it will correctly print the length of arbitrary long input lines, and as much as possible of the text.

From what I read here, I get the notion that the main routine is everything inside of main, is this correct? I posted the code for the longest-line program below for more context, but I am confused my what I am being asked to do not the code. Thanks!

#include <stdio.h>

#define MAXLINE 1000                /* maximum input line length */

int getline( char line[], int maxline );
void copy( char to[], char from[] );

/* print the longest input line */


int len;                /* current line length */
int max;                /* maximum length seen so far */
char line[MAXLINE];     /* current input line */
char longest[MAXLINE];  /* longest line saved here */

max = 0;
while (( len = getline( line, MAXLINE )) > 0)
    if ( len > max ) {
        max = len;
        copy( longest, line );
if ( max > 0 )
    printf( "%s", longest );        
return 0;

/* getline: read a line into s, return length */ 
int getline( 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;

/* copy: copy 'from' into 'to'; assume to is big enough */
void copy( char to[], char from[] ) 
    int i;

    i = 0;
    while ( (to[i] = from[i] ) != '\0' )
  • 3
    K&R isn't a great book to actually learn C from, largely because of its age Apr 7, 2014 at 13:08
  • @ratchetfreak I am reading it along with the course a VTC course here vtc.com/products/cprogramming2007.htm, I also read most of the C portion of C how to Program by Dietel last summer. But I like K & R because it is very concise. Do you know of any concise books similar to K&R that are more recent? Apr 7, 2014 at 13:16
  • 1
    Personally, I'd recommend C: The Complete Reference by Herbert Schildt although later editions are fairly weighty...
    – Robbie Dee
    Apr 7, 2014 at 15:02
  • @RobbieDee Thanks, I looked through the table of contents. The first seven chapters kind of follow K&R which is nice, and I see that there is a lot of useful material not covered in K&R. Apr 7, 2014 at 15:14
  • 1
    There is "The C Answer Book" which "Provides solutions to all exercises in Kernighan & Ritchie's new ANSI C book. Ideal for use with K&R in any course on C. Careful study of this answer book will help understand ANSI C and enhance programming skills. Tondo & Gimpel describe each solution and completely format programs to show the logical flow." I've not read it.
    – msw
    Apr 7, 2014 at 16:05

1 Answer 1


Yes, the term main routine typically means the routine (AKA function, method, etc) named main, which is the entry-point of a C program. From Wikipedia:

The main function serves a special purpose in C programs; the run-time environment calls the main function to begin program execution.

  • Thanks for confirming this. I was unsure what the question meant by "change the main routine"; I kept wanting to change the functions not the main routine, that is why I want to clarify that, that was not what the question wanted. After, confirming this I thought of away to answer the question, by only changing main while leaving the functions untouched and still in use. Apr 7, 2014 at 15:08
  • Sure. It sounds like the challenge was to figure out a solution without changing the subroutines. Apr 7, 2014 at 15:24

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