Lecture Notes on Writing a Program for Computing Averages

Overview of Program

• Goal: Compute the average of a list of non-exam scores entered by the user.
• User Input: The user can enter as many scores as they want.
• Termination: The user enters a negative number to signal the end of input.

Variables Needed

• double sum: To keep track of the total sum of scores.
• int numStudents: To count the number of scores entered.
• Scanner keyboard: To read user input.
• double next: To hold the next entered score.

Program Steps

1. Prompt User: Ask the user to enter scores and a negative number to finish.
2. Initialize Variables: Set sum, numStudents, and next to zero.
3. Reading Scores:
   • Use a loop to read scores and add to sum.
   • Increment numStudents for each score.
4. Loop Condition: Continue while next >= 0.
5. Compute Average: After loop, divide sum by numStudents.
6. Output Result: Print the computed average.

Allow Multiple Class Averages

• Prompt for New Calculation: Ask if user wants to compute another average.
• Loop for New Class: Use a loop for new class input based on user response (yes/no).
• Reset Variables: Reinitialize sum and numStudents for each new class.

Nested Loops

• Use a do-while loop to handle multiple class computations.
• Boolean Expression: Loop while user answers "yes".

Handling User Input

• Yes/No Input: Use equalsIgnoreCase to handle different cases for "yes" input.
• Guard Against Divide by Zero: Check numStudents is not zero before computing average.

Nested Loops Example

• Printing a matrix of numbers using nested loops.
• Outer Loop: Controls rows.
• Inner Loop: Controls columns.
• Row and Column Variables: Increment appropriately to print matrix.

Break and Continue in Loops

• Break: Ends the loop immediately.
  • Used in conditional statements to exit loops.
• Continue: Skips to the next iteration of the loop.
  • Used to skip remaining loop body based on condition.

Debugging Techniques

• Use Debugger: Utilize built-in debugging tools in IDEs like Eclipse.
• Temporary Print Statements: Insert print statements to monitor variable values and program flow.

Key Takeaways

• Avoid using break and continue excessively as it can lead to complex and hard-to-maintain code.
• Ensure variables are initialized and reinitialized properly within loops.
• Proper loop design can eliminate the need for redundant code.