MAXLINELEN
file1done = !fgets(line1, MAXLINELEN, fp1);
file2done = !fgets(line2, MAXLINELEN, fp2);
} while (fgets(buf, MAXLINELEN, fp));
char *p, line1[MAXLINELEN], line2[MAXLINELEN];
char line1[MAXLINELEN], line2[MAXLINELEN];
if ((int)i > last_line_end + MAXLINELEN)