Newline

Microsoft Windows uses CRLF to represent a newline.

The ugly part is the quote marks on two adjacent lines that mean a newline character.

The calculator program starts off by printing the string "0\n", that is, it prints a zero and then moves to a newline.

Unlike in C, you don't have to loop through the output and watch every character to make sure it's a newline; Perl will keep track of that for you.

It contains only a single statement, which outputs a newline character. (That's what happens when you use a print command without any arguments.)

The original Unix regex tools worked on a line-by-line basis, so the thought of matching a newline wasn't an issue until the advent of sed and lex.