Download Karel – Chapter 6 Instructions That Repeat Note: Original slides provided by...
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Karel – Chapter 6 Instructions That Repeat
Note: Original slides provided by www.apComputerScience.com and modified for Mr. Smith’s AP Computer Science A class
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Iteration Graphic Organizer Control structures
Methods
Sequential
Iteration
Conditional
Types of control structures
Types of loops
Java statement
Syntax Examples:
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Iteration (Loops) • Loops repeat a set of instructions • Two types of loops: – Definite loops ( for loops ) perform instructions an explicit number of times – Indefinite loops ( while loops ) perform instructions an indefinite number of times (until a certain test fails)
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Definite vs. Indefinite Loop? A new class you’re writing has a method with the following signature: public void move (int numMoves) – Should it be implemented with a definite loop or an indefinite loop? Justify your answer. – Could it be implemented with the other type of loop? If so, should we? Is it a good idea or bad idea? 4
Iteration Graphic Organizer Control structures
Methods
Sequential
Iteration
Conditional
Types of control structures
Definite Loops
Types of loops
Indefinite Loops
for
Java statement
while
Syntax Examples:
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for Loops General syntax: for ( ; ; ) { }
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for Loops (cont.) • sets a variable/identifier to a certain value (variable is usually count, i, j) • is a test that is evaluated each time the body is about to be executed (when false, the loop is exited) • changes the loop control variable (usually i++ or i--). The incrementing is done at the bottom of the loop. • i++ means “add 1 to i”. • i-- means “subtract 1 from i”. 7