Program Structures

Chapter 5

5

BranchingAllows different code to execute based on a conditional test.if, if-else, and switch statements

5

If, Else, and Else-Ifif Statements

“If the sky is blue, I’ll ride my bike.”

else Statements“If the sky is red, I’ll drive; else (otherwise) I’ll ride my bike.”

Else-if Idioms“If the sky is blue, I’ll ride my bike; else if the sky is red, I’ll drive, else I’ll walk.”

5

Nested if Statementsif statements can be nested (combined) within other if statements to account for multiple conditions.

If the sky is blueIf there are clouds in the sky

Do something for blue sky, cloudy days

ElseDo something for blue sky, cloudless days

ElseDo something for non-blue sky days

5

The switch Statementswitch statements are an efficient way to choose between multiple options.

Easier to expand options than else-if structuresEasier to read than multiple else-if structuresUse the break keyword to prevent “falling through” to next statement

5

Switch Evaluationswitch statements evaluate int values:

int x = 3;switch(x){ 1: x += 2; break; 2: x *= 2; break; 3: x /= 2; break;}

5

Logical OperatorsCombine or negate conditional tests

Logical AND (&&)“The value of x is greater than 10 and the value of x is less than 20”(x > 10) && (x < 20);

Logical OR (||)“The value of x is greater than 10 or the value of x is lessthan 5”(x > 10) || (x < 5);

Logical NOT (!)“The value of x is not greater than 10”! (x > 10);

5

LoopingWhat is iteration?

Iteration is a structure that repeats a block of code a certain number of times, or until a certain condition is met.

5

The while Loop“As long as this condition is true,

execute this code”while ( counter < 11){ counter++;}

Might not execute if the condition is already false

5

The for LoopIncludes (optional) arguments for:

An initialization variable

A conditional test

An action

for ( int counter = 1; counter < 11; counter++ )

{

System.out.print(counter + “ ”)

}

5

The do...while Loop“Take this action, while this is true”

int value = 10;do{ value = value + 2;}while ( value < 10 );

Ensures at least one execution of code