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Python

Ivana Bojcic
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.a{fill-rule:evenodd;}techdegree
Ivana Bojcic
Python Development Techdegree Student 892 Points
Posted by Ivana Bojcic
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Ivana Bojcic
Python Development Techdegree Student 892 Points

Exception Flow Quiz - frustrated

This is the first quiz where I just cannot get things right. Someone care to explain it to me? Is this question text maybe missing something? How can I "trace the print output" if I cannot see what is being typed and which except error is shown? :( I suppose I should read out something from result = "test" + 5 but I cannot figure out what. This is the point where I'm beginning to understand I'm not fit for programming. :((

Trace the print output of the following code:

print("A") try: result = "test" + 5 print("B") except ValueError: print("C") except TypeError: print("D") else: print("E") print("F")

Steven Parker
Steven Parker
231,198 Points
Steven Parker
Steven Parker
231,198 Points

It's not clear what course and lesson you are referring to. You might want to take a look at this video about Posting a Question

Also make sure posted code is properly formatted. Take a look at this videos about using Markdown formatting to preserve the code's appearance. And for when your question refers to something you are doing in a workspace, you may also want to view this one about sharing a snapshot of your workspace.

2 Answers

Steven Parker
Steven Parker
231,198 Points
Steven Parker
Steven Parker
231,198 Points

Learning programming is more a matter of persistence than innate ability.   :wink:

This exercise is about learning to look at the code and predict what it will do:

print("A")                # you know this will print the letter "A"
try:                      # this will cause the program flow to change based on errors
    result = "test" + 5   # adding a number to a string will cause a TypeError
    print("B")            # so this line will get skipped
except ValueError:        # this code is for a different kind of error, also skipped
    print("C")            # so this line will get skipped as well
except TypeError:         # here's where instructions will resume
    print("D")            # now the letter "D" will be printed
else:                     # this code is only for when there is NO error
    print("E")            # so this line will get skipped
print("F")                # now the letter "F" will be printed

So this code will print "A",'D", and "F", each on a separate line.

Steven Parker
Steven Parker
231,198 Points
Steven Parker
Steven Parker
231,198 Points

You're right that if the code is changed so there is no error then "B" will be printed. And "E" will also be printed.

And you are also right that lines that are not indented are not related to the "try" block. This guarantees that "A" will be printed first and "F" will be printed last regardless of what happens in the middle. I would assume this is the intentional design of the program and not that either line is "standing there randomly".

Ivana Bojcic
seal-mask
.a{fill-rule:evenodd;}techdegree
Ivana Bojcic
Python Development Techdegree Student 892 Points
Ivana Bojcic
.a{fill-rule:evenodd;}techdegree
Ivana Bojcic
Python Development Techdegree Student 892 Points

Thanks, Steven. Hypothetically, let's say there's no error. If the result is, for example: result = "test" + "test2" then why doesn't it print("B")? Because, you say for else: "this code is only for when there is NO error" If there is no error, wouldn't the solution be print("B")?

Extra question: I see that print("F") is not indented. It seems like it has nothing to do with try, except and else. Just standing there randomly, am I right?

Thanks