Program Structures Chapter 5

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

5 If, Else, and Else-If if 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 Statements if statements can be nested (combined) within other if statements to account for multiple conditions. If the sky is blue If there are clouds in the sky Do something for blue sky, cloudy days Else Do something for blue sky, cloudless days Else Do something for non-blue sky days

5 The switch Statement switch statements are an efficient way to choose between multiple options. Easier to expand options than else-if structures Easier to read than multiple else-if structures Use the break keyword to prevent “falling through” to next statement

5 Switch Evaluation switch statements evaluate int values: int x = 3; switch(x) { 1: x += 2; break; 2: x *= 2; break; 3: x /= 2; break; }

5 Logical Operators Combine 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 less than 5” (x > 10) || (x < 5); Logical NOT ( ! ) “The value of x is not greater than 10” ! (x > 10);

5 Looping What 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 Loop Includes (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