Java Chapter 5: Iteration Control Structures

Chapter 5: Repetition/Iteration Control Structures

• This chapter covers repetition control structures in programming, specifically focusing on Java programs.
• The discussion includes solving problems using repetition and flowcharting, along with pseudocode.
• A key element is writing Java programs using while, do-while, and for loops.

Loop Concepts

• Iteration control involves repeating statements or blocks of code.

• Each loop must have three parts for proper execution:

  • Initialization of a control variable.
  • Testing the control variable.
  • Updating the control variable.

• There are three types of iteration loops:

  • while loop (pre-test loop)
  • do-while loop (post-test loop)
  • for loop

while Loop

• Similar to do-while loop, but the condition is placed at the top of the loop.
• A while loop performs its code block only if the condition is true.
• Complex conditional operators can be used to assess conditions.

do-while Loop

• The code block will execute at least once, regardless of the condition.
• The condition for the do-while loop is placed at the bottom.

Problem #1

• Display "Hello" 1000 times.
• After the iterations, display "Done!"
• This exemplifies a task needing repetitive code blocks.

Phase 1: Problem Analysis

• Input: A counter initialized to 1.
• Process:
  • While the counter is less than or equal to 1000:
    • Display "Hello".
    • Increment the counter.
• Output: "Done!" when the counter reaches 1000.

Phase 2: Program Design

• Initialize a counter to 1.
• Repeat:
  • Display “HELLO”.
  • Increment counter.
• Until the counter exceeds 1000.
• Display "Done!"

Problem #2

• Create a program to guess a favorite number between 0 and 100.
• The program should only stop when the correct guess (12) is made.

Analysis Table

• Input: fav_number (the player's guess).
• Process:
  • Prompt for fav_number.
  • Get fav_number from the user.
  • Repeat the above as long as fav_number is not equal to 12.
• Output: The message "Good Guess!"

Pseudocode

• Guessing_number
• fav_number is 12
• REPEAT
  • Prompt fav_number
  • Get fav_number
• UNTIL (fav_number != 12)
  • Display "Good guess!"
• END

Flowchart

• The flowchart illustrates the steps involved in the program, showing the loop logic to repeatedly prompt and check user input until the desired number is entered correctly.

do...while loop / repeat..until loop

• Syntax:
  • Initialize control
  • do{ statement(s); update control; } while (boolean expression)

Example

• Initialize fav_number to 12.
• Prompt the user to enter a number.
• Get the entered fav_number.
• Check if fav_number is not equal to 12. If true, repeat the previous steps. If false, Display "Good guess!" as the output.

This quiz focuses on Chapter 5 of Java programming, covering repetition control structures such as while, do-while, and for loops. You'll explore the key elements of iteration control, including initialization, testing, and updating control variables. Prepare to solve problems using flowcharts and pseudocode alongside Java programming techniques.