Concatenating strings with integers and floats?

user_13401196 0
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Sup guys and gals, I'm in the very beginnings of learning to code with python and am building a very basic percentage calculator to get the gears turning mentally.

I am having an issue with running a successful flow-through with the program:

#Percentage Calculator

print('Enter value of percent: ') #prompt user for input of percent value
percent = input() #gain user input about percent *stored as 'str'
percent = int(percent) #store and convert user input into an 'int' from 'str' for use in line 11

print('Enter value of percentaged number: ') #prompt user for input of percentaged number value
percentagedNum = input() #gain user input on percentaged number *stored as 'str'
percentagedNum = int(percentagedNum) #store and convert value from 'str' into 'int'

answer = percent / percentagedNum #calculate percentage formula

print(percent + '% of ' + percentagedNum + ' is ' + answer) #prompt user with answer

Also, the traceback:

Traceback (most recent call last):
  File "C:\Program Files\JetBrains\PyCharm Community Edition 2020.1\plugins\python-ce\helpers\pydev\pydevd.py", line 1438, in _exec
    pydev_imports.execfile(file, globals, locals)  # execute the script
  File "C:\Program Files\JetBrains\PyCharm Community Edition 2020.1\plugins\python-ce\helpers\pydev\_pydev_imps\_pydev_execfile.py", line 18, in execfile
    exec(compile(contents+"\n", file, 'exec'), glob, loc)
  File "C:/Users/Custom/PycharmProjects/PercentageCalculator/main", line 12, in <module>
    print(percent + '% of ' + percentagedNum + ' is ' + answer)
TypeError: unsupported operand type(s) for +: 'int' and 'str'

I feel it's a concatenation issue with mixing strings, integers, and floats in the final print() function call.

Getting some good eyes on this would be greatly appreciated and thanks for all you guys do to help out the community. Much love.

concatenation python
2 Answers

you need to first cast the numbers as strings. you can do this explicitly:

print(str(percent) + '% of ' + str(percentagedNum) + ' is ' + str(answer))

or you can let Python f-strings take care of it:

print(f'{percent} % of {percentagedNum} is {answer}')

the reason what you were trying didn't work is that the + operator has different results depending on what was given to it. If it has strings on either side, it concatenates:

>>> "foo" + "bar"
"foobar"

if it has integers on either side, it adds them:

>>> 5 + 3
8

When you mix the input types, it's not sure what it's supposed to do.

user_110516110

In your print statement, make sure that you turn variables that contain numbers into strings by using str(): str(percent) and so on.

Indeed it's a classic error when you begin Python.

user_4792510
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