longest-line.c

# include <stdio.h>
# define MAXLINE 1000

int cgetl(char line[], int maxline, FILE * file);
void copy(char to[], char from[]);

int main () {
  int len;  
  int max;  
  char line[MAXLINE]; 
  char longest[MAXLINE]; 
  FILE * pFile;
  pFile=fopen("t.txt", "r");
  max = 0;
  while((len = cgetl(line, MAXLINE, pFile)) > 0){
    if (len > max){
      max = len;
      copy(longest, line);
    }
  }
  if (max > 0) {
    printf("%s", longest);
  }
  return 0;
}

int cgetl (char s[], int lim, FILE * f) {
  int c, i;
  for (i=0; i < lim - 1 && (c=fgetc(f)) != 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]) != '\0' ){
    ++i;
  }
}