I am trying to read 1 line and I am not sure how newline char is represented. Should I consider it as 2 chars or 1 char, when reading it from file by fgets() ? For example, I have a line of 15 chars + new line in file. So how should I safely allocate string and read that line?
At first, I tried this:
char buf[16];
fgets(buf, 16, f);
It read the line correctly without newline char and I assume that buf[15] holds the null character.
However, when I want to read and store the newline char, it doesn't work as I thought. As far as I know, '\n' should be considered as one char and take just one byte, so to read it, I just need to read one more char.
But when i try this
char buf[17];
fgets(buf, 17, f);
it does completely the same thing than previous example - there is now newline char stored in my string (I am not sure where null char is stored in this case)
To read entire line with newline I need to do this
char buf[18];
fgets(buf, 18, f);
OR this (it works, but I am not sure if it's safe)
char buf[17];
fgets(buf, 18, f);
So the questions is, why do I need to allocate and read 18 chars, when the line has only 15 chars + newline?
You need to provide buffer space for the 15-chars of text, up to 2 characters for the new line (to handle Windows line termination of \r\n), and one more for the null termination. So that's 18.
Like you did here:
char buf[18]; fgets(buf, 18, f);
The num parameter to fgets tells the call the size of your buffer it's writing to.