K&R C (second edition) causes segfault?

[icy ibex]

#include <stdio.h>                                                  
#define MAXLINE 100

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

int main() {
  int len;
  int max;
  char line[MAXLINE];
  char 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;
}

int getline(char s[], int lim) {
  int c, i;

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

  i = 0;
  while((to[i] = from[i]) != '\n') {
    ++i;
  }
}```
Pretty much, this code segfaults, it comes from 1.9 Character arrays.
When I remove `s[i] = '\0'` it compiles and runs fine.
Commands I've used for compiling is `cc characterarrays.c -std=c99`

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[icy ibex]

okay okay, does old C99 have \n\0 at the end of character arrays, and modern C only have \0?

[sage marsh]

  int c, i;

for(int i = 0;```this is shadowing the outer `i`

[pastel plover]

what? No.
\n is the newline character, i.e. it's the line break. This is just a normal character for C like 'a', '4' or '@'.
\0 is the null-character that signals the end of the string.

[sage marsh]

so when you use i outside of the loop you're actually just accessing an indeterminate value

also I'm confused why copy is using \n as the terminator

s[i] == c; this line is also wrong

[sage marsh]

especially since if you write a too long line there wouldn't be a new line

(i.e. fixing the above stuff mentioned, inputting more than 98 characters on a single line still crashes)

or if you just don't send a new line at the end