CPS 1 - Spring, 1997 - Ramm 1/24/97 #4

Chapter 1. An Intro to Programming: Coding Decision Trees

Decision Tree

Can't get car's engine to run; what is the problem?
was car just running and quit now?	yes	is gas gauge on empty?	yes	get gas
			no	call tow truck
	no	does engine crank?	yes	check gas
			no	check battery

More on Syntax
- BEGIN and END are not statements.
Add second level to decision tree
carb.pas
Limitations: 'yes' vs 'YES' vs 'Y' vs 'y'
More complicated examples: Using more than one variable.
IF-THEN: can use for simplest cases (No ELSE)
IF-THEN: can use for multi-way decision
readln(color); if color = 'red' then writeln('Keep going.'); if color = 'yellow' then writeln('You need to go faster!'); if color = 'red' then
writeln('I guess you should stop.');
Turbo Pascal Summary (Syntax Description)
- more formal method
1. <identifier> -> //a sequence of letters and/or digists that begin with a letter//
  where // indicates italics in textbook
  read: an object called an 'identifier' can be ...
1. <compound statement> -> begin
  //a sequence of <statements>s
  each followed by a semicolon//
  end
To Use: substitute, multiple times as necessary:
Statement examples
EXAMPLE:
<statement> -> writeln(<string expression>)
<statement> -> writeln(<identifier>)
<statement> -> writeln(msg1)

EXAMPLE:
#4 <statement> -> writeln(<string expression>)
#3 <statement> -> writeln('//any string//')
<statement> -> writeln('Hi there!')

Example involving compound statement
Example: want


	begin
	
readln(msg);
	
writeln(msg);

end