How to fgets() a specific line from a file in C?

Question

So, I'm trying to find a way to fgets() a specific line in a text file in C, to copy the contents of the line into a more permanent buffer:

Essentially, I was wondering if there was a way to do that without something similar to the following code:

FILE *fp;
fp = fopen(filename, "r");

char line[256];
char * buffer;
int targetline = 10;
while( targetline > 0)
{
    fgets(line, 256, fp)
}

buffer =(char*)malloc(sizeof(char) * strlen(line));
strcpy(buffer, line);

So basically I don't want to iterate through the file n-1 times just to get to the nth line... it just doesn't seem very efficient (and, this being homework, I need to get a 100% haha).

Any help would be appreciated.

Answer 1

Unless you know something more about the file, you can't access specific lines at random. New lines are delimited by the presence of line end characters and they can, in general, occur anywhere. Text files do not come with a map or index that would allow you to skip to the n^th line.

If you knew that, say, every line in the file was the same length, then you could use random access to jump to a particular line. Without extra knowledge of this sort you simply have no choice but to iterate through the entire file until you reach your desired line.