**Anguilla Library Computer Club**

Resources
# BASIC Programming Lesson #1

The point of this lesson is to introduce you to the **BASIC** programming
language. A computer language is a way of specifying exactly what a computer
should do, step by step, like a recipe for a very stupid cook. Find
BASIC on your menu and run it.
If you are already in BASIC, clear the previous person's program by doing **ALT-F**, **N** for New, then
**N** to discard changes.
## Activity: Magic Number Guessing Program

You will now write a game program.
In programming, most keystrokes
must be **exactly right.** If you make a typing mistake, the computer may complain when you finish the line, or later when you try to run the program, or not at all because
what you typed by mistake is a valid program.
This is the worst, since your program is **not** doing what you intended but the computer can't tell you. For example, in line 20 below, if you
put = instead of + that is wrong, but not an error.
let low = 0
let high = 100
print "--Write down a secret number between "; low; " and "; high
20 let guess = int ( ( low + high + .5 ) / 2)
print "Is your secret number "; guess; "?"
print "Answer L if ";guess" is too low, H if too high, C if Correct:";
input answer$
if (answer$ = "C") then goto 100
if (answer$ = "H") then high = guess
if (answer$ = "L") then low = guess
goto 20
100 print "I got it!"

Think of a number between 0 and 100, but don't tell the computer. To
play the number-guessing game, hit the following three keys
one after the other: **Alt R Enter**.
Alt brings up the menus, R selects Run and Enter selects Start.
If you typed in the game correctly, it will be able to guess your
secret number by asking you simple questions.
When you type your answers to the games, press Enter after each line.
This is what is should look like if your secret number is 75:
--Write down a secret number between 0 and 100
Is your secret number 50?
Answer L if 50 is too low, H if too high, C if correct:**L**
Is your secret number 75?
Answer L if 75 is too low, H if too high, C if correct:**C**
I got it!

Did your program have any **syntax** errors when you tried to run it?
This is usually due to typing mistakes. Ask your instructor for help. What happens if you enter lower-case "l" and "c"? Why?

- Can you modify the program so it guesses a person's number between 1
and 1000?
- Can you sometimes calculate what number the computer is going to
guess next?
- Can you modify the program so that you are given the option to play
again?