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For each job, say whether you would look before you leap (an if) or try and catch (try and except)…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
For each job, say whether you would look before you leap (an if) or try and catch (try and except), and why.
- Get the mark of a student from a dictionary, and show
no markif there is none. - Turn the text that a user typed into a whole number.
- Take the first item of a list that may be empty.
- Divide by a number that may be zero.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Plan. If one short if makes the check, look first. If the check is as hard as the job, try and catch.
- Either.
if name in marksis a short check.marks.get(name, "no mark")is shorter still. Look before you leap fits well. - Try and catch. To check in advance that a text is a whole number, you would have to think about signs and digits.
int()already knows, so usetrywithexcept ValueError. - Look before you leap.
if items:is a short check: an empty list isFalse. Then useitems[0]. - Look before you leap.
if divisor != 0:is short and clear. (Try and catch withZeroDivisionErroralso works.)
Check. Ask: is the check shorter and easier than the job? If yes, check first.
Answer: look (or get), try, look, look.
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