Linear search with a FOR loop and a Found flag

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Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. Which line correctly sets up the flag before a linear search loop?

A Found ← FALSE

B Found ← TRUE

2. Which declaration is correct for the Found flag?

A DECLARE Found : STRING

B DECLARE Found : BOOLEAN

3. Where should Found ← FALSE be placed?

A Inside the loop, as its first line

B Before the FOR loop starts

4. Which IF statement inside the loop checks the current element against the target?

A IF Names[Index] = Target THEN

B IF Names = Target THEN

5. What happens when Names[Index] = Target is true?

A Found ← TRUE

B Found ← FALSE

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1Found ← FALSE		ADECLARE Found : BOOLEAN
2IF Names[Index] = Target THEN Found ← TRUE		BCompares the current array element with the target and sets the flag to TRUE if they are equal
3Declare a BOOLEAN variable to hold whether the target was found		CThe output line assigns TRUE to Found instead of reporting the result, so it always shows a match. It should output Found or a message based on its value.
4After the loop ends, output a message only if the flag shows the target was seen		DIF Found = TRUE THEN OUTPUT "Found" ELSE OUTPUT "Not found" ENDIF
5FOR Index ← 1 TO 5 Found ← FALSE IF Names[Index] = Target THEN Found ← TRUE NEXT Index		ESets the flag to FALSE before the loop starts, meaning the target has not been seen yet
6FOR Index ← 1 TO 5 IF Names[Index] = Target THEN Found ← TRUE NEXT Index OUTPUT Found ← TRUE		FFound ← FALSE is inside the loop, so it resets the flag on every pass and a match can be lost. It must be set once before the loop.

Definitions

Found ← FALSE

Fill in the Blanks

Complete each line of code by filling in the missing parts.

DECLARE Found : _______ DECLARE Index : INTEGER

Found ← _____ FOR Index ← 1 TO 5 IF Names[Index] = Target THEN

FOR Index ← 1 TO 5 IF Names[Index] _ Target THEN Found ← TRUE

IF Names[Index] = Target THEN Found ← ____ ENDIF

NEXT Index IF _____ = TRUE THEN OUTPUT "Name found"

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A Found ← FALSE

B FOR Pos ← 1 TO 5

C IF Names[Pos] = Target THEN

D Found ← FALSE

E ENDIF

F NEXT Pos

Question 2

A Found ← TRUE

B FOR Pos ← 1 TO 8

C IF Teams[Pos] = Target THEN

D Found ← TRUE

E ENDIF

F NEXT Pos

Question 3

A Found ← FALSE

B FOR Pos ← 1 TO 6

C IF Names[Pos] <> Target THEN

D Found ← TRUE

E ENDIF

F NEXT Pos

Question 4

A Found ← FALSE

B FOR Pos ← 1 TO 4

C IF Words[Pos] = Target THEN

D Found = TRUE

E ENDIF

F NEXT Pos

Question 5

A IF Found = FALSE THEN

B OUTPUT "Found"

C ELSE

D OUTPUT "Not found"

E ENDIF

Answer Key

Linear search with a FOR loop and a Found flag

Section A: Quick Questions

A — Found ← FALSE

B — DECLARE Found : BOOLEAN

B — Before the FOR loop starts

A — IF Names[Index] = Target THEN

A — Found ← TRUE

Section B: Match the Pairs

Found ← FALSE → Sets the flag to FALSE before the loop starts, meaning the target has not been seen yet

IF Names[Index] = Target THEN Found ← TRUE → Compares the current array element with the target and sets the flag to TRUE if they are equal

Declare a BOOLEAN variable to hold whether the target was found → DECLARE Found : BOOLEAN

After the loop ends, output a message only if the flag shows the target was seen → IF Found = TRUE THEN OUTPUT "Found" ELSE OUTPUT "Not found" ENDIF

FOR Index ← 1 TO 5 Found ← FALSE IF Names[Index] = Target THEN Found ← TRUE NEXT Index → Found ← FALSE is inside the loop, so it resets the flag on every pass and a match can be lost. It must be set once before the loop.

FOR Index ← 1 TO 5 IF Names[Index] = Target THEN Found ← TRUE NEXT Index OUTPUT Found ← TRUE → The output line assigns TRUE to Found instead of reporting the result, so it always shows a match. It should output Found or a message based on its value.

Section C: Definitions

Found ← FALSE — Sets a BOOLEAN flag to FALSE before a FOR loop. The loop sets Found to TRUE if an element equals the target. After the loop, Found shows whether the target was seen.

Section D: Fill in the Blanks

DECLARE Found : BOOLEAN
DECLARE Index : INTEGER

Found ← FALSE
FOR Index ← 1 TO 5
   IF Names[Index] = Target THEN

FOR Index ← 1 TO 5
   IF Names[Index] = Target THEN
      Found ← TRUE

IF Names[Index] = Target THEN
   Found ← TRUE
ENDIF

NEXT Index
IF Found = TRUE THEN
   OUTPUT "Name found"

Section E: Spot the Error

D — When the target is matched, the flag must be set to TRUE. Setting it to FALSE means the search can never record a success. It should be Found ← TRUE.

A — The flag must start as FALSE before the loop, because nothing has been found yet. Starting as TRUE would report a match even when the target is missing. It should be Found ← FALSE.

C — The search must test whether the element EQUALS the target. <> means not equal, so Found would be set for the wrong elements. It should be IF Names[Pos] = Target THEN.

D — A single = compares values. It does not store anything. To set the flag you use the assignment arrow: Found ← TRUE.

A — After the loop, the TRUE branch should report success. Testing for FALSE swaps the two messages. It should be IF Found = TRUE THEN.