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Python Python Basics (2015) Logic in Python Try and Except

Posted by Saman Bir
Saman Bir
Courses Plus Student 724 Points

Challenge Task 3 - Try and Exceptions

Hello,

Can someone help me with this?

I have problems starting from "try".

trial.py 
def add(a1, a2):
    print(float(a1) + float(a2))
    return(float(a1) + float(a2))
try:
    a1 = float(a1)
    a2 = float(a2)
except ValueError:
    return None   
else:
    return (float(a1)+float(a2))

4 Answers

taejooncho
taejooncho
Courses Plus Student 3,923 Points

Sorry about my answer being confusing. Let me clearify step by step. this is your code

def add(a1, a2):
    print(float(a1) + float(a2))      
    return(float(a1) + float(a2))   
# This was where I was telling you that was causing the issue
# if you write these two codes before try function and say a1 and a2 is like a list
# python will give you type error before running the command below.
try:    <---------#  notice how from try and below your code is not indented? 
   a1 = float(a1) # you want to indent all the code to include into function
   a2 = float(a2)
except ValueError:
    return None   
else:
    return (float(a1)+float(a2))  
#  this line was what I was saying on the side note
# you can write return a1 + a2 and it will give you same results

Your code should look like this to have no error and finish the task

def add(a1, a2):
    try:
        a1 = float(a1)
        a2 = float(a2)
    except ValueError:
        return None   
    else:
        return a1 + a2

hope this was more helpful. Sorry for not being clear on the first time

Saman Bir
PLUS
Saman Bir
Courses Plus Student 724 Points
Saman Bir
Saman Bir
Courses Plus Student 724 Points

Hello Taejooncho,

Thank you for your answer. What I really have trouble with is reading the code correctly. For instance this is how I [read] it:

def add(a1, a2):
try:
a1 = float(a1) [a1 should be a float(a1)] a2 = float(a2) [a2 should be a float(a2)] except ValueError:
return none [If its not a float don't print any result] else: return a1 + a2 [If it is a float print a1 + a2] add(3, 2.2)

When we type - try: a1 = float(a1)

How do you read it?

The above is my latest try for the challenge. I get the error - NameError: name 'add' is not defined

Sorry for typing this way. I do not know how to get the workspace n the comment section.

taejooncho
PLUS
taejooncho
Courses Plus Student 3,923 Points
taejooncho
taejooncho
Courses Plus Student 3,923 Points

Hi there,

As to why I think you are not getting pass the challenge is because of this section from your code on line 2 and line 3

    print(float(a1) + float(a2))
    return(float(a1) + float(a2))

Since you are doing return float(a1) before the try function starts, it is not working.

For example, let's say that a1 was a list like [1, 2, 3]. You can't make a list into a float, so python will give you an type error before even running the try code down below.

On a side note, when you already made a1 = float(a1) and a2 = float(a2) you can just write

else:
    a1 + a2

you do not need to rewrite float(a1) + float(a2) again.

Saman Bir
PLUS
Saman Bir
Courses Plus Student 724 Points
Saman Bir
Saman Bir
Courses Plus Student 724 Points

Thank you for your help.