Program tax check

Integer: tax_rate

real: tax%

BEGIN

tax% := 0

GET (tax_rate)

WHILE tax_rate > 0 loop

IF tax_rate > 3 THEN

tax_rate := 3

ENDIF

tax% := tax% + (tax_rate / 10)

tax_rate := tax_rate - 1

ENDLOOP

IF tax% > 0.6 THEN

print ("tax rate is high")

ELSEIF tax% < 0.1 THEN

print ("tax rate is zero")

ELSE

print ("tax rate is low")

ENDIF

END tax check

Explanation of Control Flow:

Initialization:

tax% := 0

Get Tax Rate:

GET (tax_rate)

While Loop:

Loop runs while tax_rate > 0.

Inside the loop:

If tax_rate > 3, set tax_rate to 3.

Update tax% by adding tax_rate / 10.

Decrement tax_rate by 1.

Post-Loop Condition Checks:

After the loop, check the value of tax%:

If tax% > 0.6, print "tax rate is high".

Else if tax% < 0.1, print "tax rate is zero".

Otherwise, print "tax rate is low".

Unreachable Code Analysis:

The ELSEIF tax% < 0.1 THEN condition (line 17) is unreachable.

In the loop, tax% is incremented by a minimum of 0.1 each time tax_rate is greater than 0.

Therefore, tax% cannot be less than 0.1 after the loop.

Conclusion:

Line 17 (ELSEIF tax% < 0.1 THEN) will never be true given the logic of the loop.

Reference: Analysis of control flow and unreachable code is a key aspect of understanding and

verifying software logic, as discussed in ISTQB materials​​​​.