2.8 for Loops

1. Exam Points

• for loop
  • for loop and while loop (equivalent loop)
  • for loop algorithms (ex. find sum/average)
  • for loop + string manipulation
  • loop condition is evaluated: number of iterations + 1
• Note:
  • Analyze how the loop control variable (i) changes.
  • First iteration and last iteration.
  • Use trace tables if necessary.
  • check print statements is inside the loop or outside a loop.

2. Knowledge Points

(1) for Loops

• A for loop is a type of iterative statement.
• There are three parts in a for loop header: the initialization, the Boolean expression, and the update.
  
• How a for loop is executed:
  
  • 1. initialization: int i =1
  • 2. check the Boolean expression: i <=5
  • 3. if true, execute the loop body
  • 4. increment i by 1 (i++)
  • 5. repeat steps 2 to 4 until the Boolean expression evaluates to false.
  • 6. Execution of the for loop here:
  • 7. How many times i <= 5 is evaluated? 6
• How many times each part is executed?
  
  • part 1 -> 1
  • part 2 -> n+1
  • part 3 -> n
  • part 4 -> n
• A for loop can be rewritten into an equivalent while loop (and vice versa).

3. Exercises

• Practice
• Solution