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<h1><em>The Roger Frank Lessons</em><br>
Introduction to Computer Science: GvR Unit</h1>
<h2>Guido van Robot Programming Summary</h2>
<p>
<h3>The Five Primitive Guido van Robot Instructions:</h3>
<br>
<pre>
1. move
2. turnleft
3. pickbeeper
4. putbeeper
5. turnoff
</pre>
<p>
<h3>Block Structuring</h3>
<br>
Each Guido van Robot instruction must be on a separate line.
A sequence of Guido van Robot instructions can be treated as a single
instruction by indenting the same number of spaces.
<instruction> refers to any of the five primitive instructions above,
the conditional branching or iteration instructions below,
or a user defined instruction.
<pre>
<instruction>
<instruction>
...
<instruction>
</pre>
<p>
<h3>Conditionals</h3>
<br>
GvR has eighteen built-in tests that are divided into three groups:
the first six are wall tests,<br>
the next four are beeper tests,<br>
and the last eight are compass tests:<br>
<pre>
1. front_is_clear
2. front_is_blocked
3. left_is_clear
4. left_is_blocked
5. right_is_clear
6. right_is_blocked
7. next_to_a_beeper
8. not_next_to_a_beeper
9. any_beepers_in_beeper_bag
10. no_beepers_in_beeper_bag
11. facing_north
12. not_facing_north
13. facing_south
14. not_facing_south
15. facing_east
16. not_facing_east
17. facing_west
18. not_facing_west
</pre>
<h3>Conditional Branching</h3>
<br>
Conditional branching refers to the ability of a program to alter it's flow of
execution based on the result of the evaluation of a conditional.<br>
The three types of conditional branching instructions in Guido van Robot
are <b>if</b> and <b>if/else</b> and <b>if/elif/else</b>.
<b><test></b> refers to one of the eighteen conditionals above.
<br>
<pre>
if <test>:
<instruction>
if <test>:
<instruction>
else:
<instruction>
if <test>:
<instruction>
elif <test>:
<instruction>
...
elif <test>:
<instruction>
else:
<instruction>
</pre>
<p>
<h3>Iteration</h3>
<br>
Iteration refers to the ability of a program to repeate an instruction
(or block of instructions) over and over until some condition is met.
The two types of iteration instructions are the do and while instructions.
<positive_number> must be an integer greater than 0.
<pre>
do <positive_number>:
<instruction>
while <test>:
<instruction>
</pre>
<p>
<h3>Defining a New Instruction:</h3>
<br>
New instructions can be created for Guido van Robot using the define statement.
<new_name> can be any sequence of letters or digits as long as it begins with
a letter and is not already used as an instruction.
Letters for Guido van Robot are A..Z, a..z, and the underscore (_) character.
Guido van Robot is case sensitive, so TurnRight, turnright, and turnRight are
all different names.
<pre>
define <new_name>:
<instruction>
</pre>
<p style="text-align: center;">
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<p class="copyleft">
<a href="http://www.gnu.org/copyleft/copyleft.html">
Copyright</a> © 2003 <a href="http://www.elkner.net/">Jeffrey Elkner</a>.
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