K&R Exercise 1.16 - Limitation on line length

Question

I\'m learning C from K&R\'s \"The C Programming Language\" book. I\'m doing the exercises specified in the book. I\'m on exercise number 1.16, but I don\'t understand it

Answer 1

It's a pretty early exercise in K&R, you're just supposed to do some minor changes to the code, not a total redesign of the code.

1. "...as much as possible of the text..."

   is up to you to interpret. I'd do it by printing what's stored in the longest buffer. i.e. print out up to 1000 characters of the line. Again, it's an early exercise, with little introduction to dynamically allocated memory yet. And at the time K&R was written, storing away arbitrarily long text lines wasn't as feasible as it is today.

2. "...the length of arbitrarily long input lines..."

   Is a hard requirement. You're supposed to find the correct length no matter how long it is (at least within the bounds of an int. )

One way to solve this problem is:

• After the call to getline(), check if the last character read into the line buffer is a newline ('\n')
• If it is, you read a complete line. The len variable is the correct length of the line(the return value of getline(), and no special consideration is needed compared to to original code.
• If it is not , you did not read the entire line, and need to hunt for the end of this line. You add a while loop, calling getchar() until it returns a newline (or EOF), and count the number of characters you read in that loop. Just do len++ to count.
• When the while loop is done, the new len is now the actual length of the line, but our buffer just has the first 999 characters of it.
• As before, you store away (the copy() function call) the current line buffer (max 1000 chars) if this line is the longest so far.
• When you're done, you print out the stored line as before (the longest buffer) and the max variable for the length.
  • Due to the above mentioned while loop that max length is now correct.
  • If the longest line indeed was longer than 1000 chars. you at least print out those first 999 chars - which is "as much as possible".

I'll not spoil it and post the code you need to accomplish this, but it is just 6 lines of code that you need to add to the longest-line program of exercise 1-16.