HQ9 Plus

HQ9+ is a simple but elegant programming language that is very efficient for coding certain classes of computer programs. It has four commands, each represented by a single character: H, Q, 9, and + (hence the name).

• The H command prints out "Hello, world!"

• The Q command prints out a copy of the source code of the program.

• The 9 command prints out the lyrics for 99 Bottles of Beer on the Wall.

• The + command increments the accumulator.

An example HQ9+ program would be: "HHQ+HQ++"

This program would output "Hello, world! Hello, world! HHQ+HQ++ Hello, world! HHQ+HQ++" as well as incrementing the accumulator three times.

Of course, HQ9+ is a joke; each command represents a common task that beginners are given when learning a new programming language. A common exercise, for example, is to write a computer program that prints "Hello, world!". There are some programming languages in which this is actually quite difficult; however, in HQ9+ the task is elementary, since the program "H" will accomplish the task.