CareerCup

Use fseek() function in C. Using fseek(), if you pass negative number, then file pointer moves that number of bytes to its left, and if positive number passed, then it shifts that many bytes right.
First reach end of file using fseek(fp,0,SEEK_END) then keep coming 1 char left and appending chars to string end, each time u find a '\n', reverse the string and print it, again make the string empty and do this until required number of lines are not printed :)

generally, use the round-robin % ...the number of lines required is what to be modular-ed.

void tail(FILE *fp, int num_lines)
{
char **buffer = calloc(num_lines, sizeof(char *));
int index = 0;
int i;

for (;;)
{
char *line = NULL;
int len = 0;

if (getline(&line, &len, fp) < 0)
break;

if (buffer[index])
free(buffer[index]);

buffer[index] = line;

index++;
index %= num_lines;
}

for (i = 0; i < num_lines; i++)
puts(buffer[(index + i) % num_lines]);
}

what is a UNIX tail command?

Cirular array of size n where n stands for last n elements in the tail, shud do it , i guess.

Sweet.

Do they really expect you to know the file commands??

I mean this Q is so out of leauge from rest of the Q's that they usually ask? Was this for some specific position or did you have sth related on your resume?

I think fseek to the end and then reading char by char from reverse is the correction solution.
Circular array or queue I assume you guys are reading the whole file - if so that's not good. Imagine big file (millions of files). You shouldn't read more than what is really necessary.