Mastering Program Structures: Branching & Looping

1. Chapter 5 Program Structures

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

3. 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.”

4. 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

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

7. 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 lessthan 5” • (x > 10) || (x < 5); • Logical NOT (!) • “The value of x is not greater than 10” • ! (x > 10);

8. 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.

9. 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

10. 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 + “ ”) }

11. 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