Would this be both a semantic error and a logic error?

Question

I am an AP computer science teacher.

I gave my students this question:

Imagine that you are building a program to automate the process of buying tickets for a concert. This is pseudocode for your program:

1. Take user input ("How old are you?")

2. If user age >= 18, print "You can enter the concert but you cannot buy alcohol."

3. Else if user age >= 21, print "You can enter the concert and buy alcohol."

4. Else, print "You may not go to the concert at all."

I asked them whether this was a syntax error, logic error, or semantic error.

My intention was that they choose logic error, but the students were saying that they should be given credit if they chose semantic error.

What are your thoughts?

I was really expecting logic error, because all they had to do is reverse the positions of the first and second Boolean conditions.

Answer 1

The definition of semantic error and logic error is ambiguous.

• A logic error occurs when a program doesn’t perform as intended due to a flaw in the program’s logic or algorithm. The syntax of the code is correct, but the result is not what you expected.

• A semantic error is when a programmer misunderstands how the programming language works and writes code that doesn’t make sense in the context of the language’s rules. Hence, they could argue that this is a semantic error because they misunderstood that Python would take the first if into consideration first.

However, if this is an exam question, we must assume that they already know the basic concepts of Python, so you shouldn't give any points to students who chose semantic error.

A similar case is ZeroDivisionError, this is a runtime error, but it is also a logic error in the case that the code is a/b and b happens to be 0 unintentionally, or np.array([7]) / 0 gives array([inf]) without an error but not what the code is supposed to do.