Access file's info in MINIX

I want to make a new command in Linux(Minix) in C, for printing some info in the screen. The info is located in the file /etc/passwd and other files.
The info is names logged in, in the system and other...
I can use system() to open the file with vi editor but i don't know how to save something written in the file in a variable, so i can use it.
Anyway, i don't know if any of these is right. If you have any other ideas, please help.

Can i use fscanf() to access the file?
For example the first line of the file may be: Zuko956:92555:something
How can i store Zuko956 in a variable so i can use it?

You use the standard C file manipulation API, fopen(), fgets() and fclose(). Then you split the lines you read along the colons and you have the individual fields.

Or you could use the actual passwd info API, like getpwent(), if MINIX supports it.

Thanks once more!