compare_lines.c

#include <stdio.h>
#define MAXLINE 1000 // Maximum input line size

int get1line(char line[], int maxline);
void copy(char to[], char from[]);

// Print longest input line
int
main()
{
  int len;                // Current line lenght
  int max;                // Maximum lenght seen so far
  char line[MAXLINE];     // Current input line
  char longest[MAXLINE];  // Longest line saved here

  max = 0;
  while ((len = get1line(line, MAXLINE)) > 0)
    if (len > max) {
      max = len;
      copy(longest, line);
    }

  if (max > 0)            // There was a line to read
    printf("Longest string read is: %s", longest);

  return 0;
}

// `get1line()` : save a line from stdin into `s`, return `lenght`
int get1line(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`; assuming
// `to` is big enough.
void
copy(char to[], char from[])
{
  int i;
  
  i = 0;
  while ((to[i] = from[i]) != '\0')
    ++i;
}