Thread: beginner question - unable to view outputs while in a loop

i'm sorry, i have no idea how to word this. i'm learning c independently out of k&r on a mac. but there's a problem.

so, for example, a very simple program which prints the longest line and length of the line from an input (from k&r)

Code:

#include <stdio.h>

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

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

/* print longest input line */
main()
{
	int len, max;
	char line[MAXLINE], longest[MAXLINE];
	
	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;

	while (to[i] = from[i] != '\0')
		++ i;
}

when i compile this and run it by ./a.out, i've got the text input (from the getchar()), but the program never advances to the point where it prints the line and length. i used to be able to put in a break trigger in the getchar loop, but this doesn't work for this program. i suspect that i'm just misunderstanding the concept of EOF, but i have no idea what to do or what to search for (so forgive me if this has been answered before).

sorry again for a beginner's unknowingly bad wording. thanks for the help in advance.

In your read function, i can NEVER be anything less than 1 at the return (s[i] = '\0'; ++i

i see. however, how is it possible that i could have less than 1 character in the line? (or alternatively, just getting around this.)

if it means anything, i'm running in terminal.

Wait a minute. . . I was miss reading the code -- What I said was wrong.

How are you interacting with this program? You should be typing in lines of code. When you are done, you should send the EOF code to your program (in Linux this would be by pressing CTRL-D) if you are not redirecting a file from into stdin.

this is exactly what i was looking for. thank you.

(yeah, i'm just typing in random text. hopefully this counts as "lines of code.")

however, upon sending the EOF code to the above program, i'm still not getting anything printed. hrm.

Code:

	while (to[i] = from[i] != '\0')    
		++ i;

Don't you feel that you are missing something in while loop when you copy the code form the book?

no, i also put i = 0, which solved the problem. hence my previous post. sorry to be unclear.