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Python Python Basics (2015) Number Game App Squared

Posted by Errin E. Johnson
Errin E. Johnson
22,458 Points

Im not understanding how to check if number is an integer. Not sure if its a syntax or logic misunderstanding?

I used a try and except block to test for integer. I was thinking I could just say try: int(num) and if this is true then return ... but that didnt work. I tried saving it into a variable such as x = int(num), logic if x is an integer then return ...

Then I tried a conditional statement which is included in my final code submission. Im not sure what Im missing here

squared.py 
# EXAMPLES
# squared(5) would return 25
# squared("2") would return 4
# squared("tim") would return "timtimtim"
def squared(num):
    try:
        if num == int(num):
            return num * num
    except TypeError:
        return len(num) * num

2 Answers

Stuart Wright
Stuart Wright
41,119 Points
Stuart Wright
Stuart Wright
41,119 Points

If you pass a float, say 3.5 to that function, nothing will be returned.

It will fail the condition so num * num will not be returned, but there also won't be an error, so the except block won't be executed.

Here is one correct solution:

def squared(num):
    try:
        num = int(num)
        return num * num
    except ValueError:
        return len(num) * num
Errin E. Johnson
Errin E. Johnson
22,458 Points

Thank You, have another question. num = int(num) ; would it matter if num was called x; therefore: x = int(num)? or is num the argument understood as being the same when declared in a variable. variable x then wouldn't make sense, you couldn't give variable any name. Trying to understand how python complies and interprets this code block, what does it "see" line by line. ? The above code work correct , plus I had to change the except error to ValueError:

Stuart Wright
Stuart Wright
41,119 Points
Stuart Wright
Stuart Wright
41,119 Points

x = int(num) would be fine too. Then you would need to return x * x. There is nothing special about 'num' - it's just the variable name in this exercise. Integers are immutable so cannot be changed 'in place' . To convert to integer, it needs to be assigned to another variable. Reusing the same variable (as I've done in my example), or using another name such as x are both fine.

Alexander Davison
Alexander Davison
65,469 Points
Alexander Davison
Alexander Davison
65,469 Points

You have a logical error, not a syntactical error.

This seems to pass:

def squared(num):
    try:
        return int(num) * int(num)
    except ValueError:
        return num * len(num)
  • You should catch the ValueError error, not the TypeError error.
  • Multiplying a string by a number makes more sense then multiplying a number by a string. You don't have to change this, though.
  • You should return int(num) * int(num), because if num was the string '1', you would have to convert it to an integer before adding. Just calling int(num) won't actually change the value of num!

I hope this helps :grin:

Happy coding! :tada:

:dizzy: ~Alex :dizzy:

Errin E. Johnson
Errin E. Johnson
22,458 Points

Thank You, I need to read up on the except errors: :)

Alexander Davison
Alexander Davison
65,469 Points

To see which error a try block could cause, try doing something that the try block might do that will cause an error.

For this situation, I knew that it was a ValueError because I tested this (which is what might happen with our try block):

>>> int('a')
...
ValueError: Invalid literal for base 10: 'a'