Multiple Choice Questions on 'If/Then' within 'Repeat' Loops

💡 Quick Study Guide

• 🔄 Repeat Loops (Iteration): These structures execute a block of code multiple times. They can repeat a fixed number of times (e.g., `REPEAT 10 TIMES`) or until a certain condition is met (e.g., `REPEAT UNTIL condition_is_true`). The core idea is to automate repetitive tasks.
• 🧐 If/Then Statements (Conditional Logic): These allow a program to make decisions. If a specified condition is true, a certain block of code is executed; otherwise, it's skipped. They often include `ELSE` clauses for alternative actions.
• 🔗 Combining 'If/Then' within 'Repeat': When an `If/Then` statement is placed inside a `Repeat` loop, the condition of the `If/Then` statement is evaluated during *each* iteration of the loop. This means different actions can be taken in different passes of the loop based on changing data or states.
• ⚙️ Execution Flow: The loop continues to iterate, and with each iteration, the `If/Then` condition is checked. If true, its block runs; if false, it doesn't (or the `ELSE` block runs). This allows for dynamic behavior within a repetitive process.
• 🎯 Common Use Cases: Filtering data (e.g., "process only numbers greater than 10"), counting specific events (e.g., "count how many times a certain value appears"), searching for items, or modifying elements based on criteria during an iteration.
• ⚠️ Important Considerations:
  • 🔢 Condition Changes: Ensure the condition inside the `If/Then` can change during the loop, otherwise, it will always execute or never execute.
  • 🛑 Loop Termination: Be mindful of how the `If/Then` logic might affect variables that control the `Repeat` loop's termination.
  • 🐛 Debugging: Trace the values of variables and the conditions at each step to understand the flow, especially when unexpected results occur.

🧠 Practice Quiz

1. Consider the following pseudocode:

SET count TO 0
REPEAT 3 TIMES
    SET num TO (current iteration number + 1)
    IF num > 2 THEN
        ADD 1 TO count
    END IF
END REPEAT
PRINT count

What will be the final value of 'count'?

1. 0
2. 1
3. 2
4. 3

2. What is the primary purpose of placing an 'If/Then' statement inside a 'Repeat' loop?

1. To make the loop run indefinitely.
2. To execute a block of code only once.
3. To perform different actions based on conditions that might change during each iteration.
4. To terminate the program immediately.

3. Examine the pseudocode below:

SET total TO 0
SET i TO 1
REPEAT UNTIL i > 4
    IF i MOD 2 == 0 THEN
        ADD i TO total
    END IF
    ADD 1 TO i
END REPEAT
PRINT total

What value will be printed for 'total'?

1. 2
2. 4
3. 6
4. 10

4. A programmer wants to find the first number greater than 50 in a list of 100 numbers and stop processing. Which combination would be most efficient?

1. A `REPEAT` loop with an `IF/THEN` condition, but no `BREAK` or `EXIT` mechanism.
2. A single `IF/THEN` statement without a loop.
3. A `REPEAT` loop with an `IF/THEN` condition that includes a `BREAK` or `EXIT` statement.
4. A `REPEAT` loop that runs 100 times, checking the condition in each iteration but never stopping early.

5. What will be the output of this pseudocode?

SET result TO ""
SET char_code TO 65 // 'A'
REPEAT 3 TIMES
    IF char_code MOD 2 == 0 THEN
        APPEND CHAR(char_code) TO result
    END IF
    ADD 1 TO char_code
END REPEAT
PRINT result

1. A
2. B
3. AB
4. BC

6. Consider a 'Repeat' loop designed to process user input until "STOP" is entered. Inside this loop, an 'If/Then' statement checks if the input is a valid number. What happens if the user enters "HELLO"?

1. The program will crash because "HELLO" is not a number.
2. The 'If/Then' condition for a valid number will be false, and the loop will continue to the next iteration (unless "HELLO" is the stop word).
3. The loop will terminate immediately.
4. The 'If/Then' statement will automatically convert "HELLO" to a number.

7. Which scenario best describes an appropriate use of an 'If/Then' statement *within* a 'Repeat' loop?

1. Setting up the initial value of a counter before the loop begins.
2. Defining how many times the loop should run.
3. Changing the color of a pixel only if its brightness is above a certain threshold, for every pixel in an image.
4. Printing a "Loop Finished" message after the loop has completely ended.