File input/output is part of Short Circuit's Console Program Basics selection.
Task

Create a file called   "output.txt",   and place in it the contents of the file   "input.txt",   via an intermediate variable.

In other words, your program will demonstrate:

   how to read from a file into a variable
   how to write a variable's contents into a file


Oneliners that skip the intermediate variable are of secondary interest — operating systems have copy commands for that.




file i, o;
text s;
 
i.open("input.txt", OPEN_READONLY, 0);
o.open("output.txt", OPEN_CREATE | OPEN_TRUNCATE | OPEN_WRITEONLY,
       0644);
 
while (i.line(s) ^ -1) {
    o.text(s);
    o.byte('\n');
}