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pythonnameerror
Questions
Questions

Reputation: 115

I defined a <variable> in an if-else, but why is there an error "the name <variable> is not defined"?

Why is there an error

the name 'output' is not defined?

weight = input('> ')
converter = input('lbs or kg: ').lower()

if converter == 'l':
    output = weight * 2.205 + 'lbs'
elif converter == 'k':
    output = weight / 2.205 + 'kg'
    
print(f'converted weight = {str(output)}')

Upvotes: 0

Views: 846

Answers (5)

Nishad C M
Nishad C M

Reputation: 174

def main () :
    weight = input('> ')
    converter = input('lbs or kg: ').lower()
    try :
        weight = float(weight)
        if converter[0] == 'l':
            output = str(weight * 2.205) + 'lbs'
        elif converter[0] == 'k':
            output = str(weight / 2.205) + 'kg'
        else:
            output = "Invalid option"
    except Exception as e:
        output = "Invalid Weight"

    print(f'converted weight = {str(output)}')

Upvotes: 0

user9706
user9706

Reputation:

I had to tweak the output a bit to make it work:

weight = input('> ')
converter = input('lbs or kg: ').lower()

if converter == 'l':
    output = str(float(weight) * 2.205) + 'lbs'
elif converter == 'k':
    output = str(float(weight) / 2.205) + 'kg'
else:
    output = 'fail'
    
print(f'converted weight = {output}')

Upvotes: 0

atin
atin

Reputation: 903

When the converter is neither l nor k then both conditions are false and hence output is never created that's why you are getting this error. To resolve this issue you have to create a variable named output before the conditional statements(if and elif)

output = ""
# rest of your code here

Upvotes: 0

Ami Tavory
Ami Tavory

Reputation: 76396

If converter is not 'l' or 'k', then no output = ... is never executed.

You can precede the conditionals by

output = <some default value>

or raise an exception if no condition was met.

Upvotes: 2

Jarvis
Jarvis

Reputation: 8564

What would happen if the value of converter is not 'l' neither 'k'? The code inside your conditionals would never get executed and hence output would never be assigned.

You should declare output before your conditionals to have a default value at-least in case none of your conditions are satisfied like this:

output = ""
weight = input('> ')
converter = input('lbs or kg: ').lower()

if converter == 'l':
    output = weight * 2.205 + 'lbs'
elif converter == 'k':
    output = weight / 2.205 + 'kg'

print(f'converted weight = {str(output)}')

Upvotes: 1

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