Thread: K&R Chapter 1 - basic question

Hi,

I am new to C and I have a very basic question regarding the example in paragraph 1.9 of K&R (reproduced below).

I managed to run the program through the Terminal of my Mac, but I do not understand how it works. Especially, I do not understand how the program captured my input and fed it as an argument to the getline_kr function. Indeed, I do not see the array line being assigned to a value anywhere. I would have expected a statement akin to the raw_input() function in Python.

Could anyone explain how the text that I type in the terminal after the program is launched ends up being assigned to the line array????

Thank you for your help.

Code:

#include <stdio.h>


#define MAXLINE 1000


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


int main(void)
{
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_kr(line, MAXLINE)) > 0) /* QUESTION: WHERE IS LINE ASSIGNED A VALUE??????? */
        if (len > max) {
            max = len;
            copy(longest, line);
        }

if (max > 0) /* there was a line */
        printf("%s", longest);
    return 0;
}


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


int getline_kr(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 its big enough */


void copy(char to[], char from[])
{
    int i;

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

Ah, I think I get it. It is the getchar() function that reads my input one character at a time.