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+--- Thread: Resolving unsupported operand type +=: 'int' and 'str' (/thread-21011.html)
Resolving unsupported operand type +=: 'int' and 'str' - jedmond2 - Sep-10-2019
Very new to programming here and this is a homework question.
The output I'm trying to generate looks as follows:
ENTER ITEMS (ENTER 0 TO END)
Cost of item: 152.50
Cost of item: 59.80
Cost of item: 0
Total: 212.3
Sales tax: 12.74
Total after tax: 225.04
Again? (y/n): n
Thanks, bye!
The code I've created so far is as follows:
#!/usr/bin/env python3
def get_cost():
total_cost = 0
while True:
print("ENTER ITEMS (ENTER 0 TO END)")
cost = str(input("Cost of item: "))
if cost == 0:
print_cost(total_cost)
break
else:
total_cost += cost
def print_cost(total_cost):
print("Total: " + str(total_cost))
print("Sales tax: " + str(total_cost * .06))
print("Total after tax: " + str(total_cost + (total_cost * .06)))
print()
def main():
print("Sales Tax Calculator")
print()
choice = "y"
while choice.lower() == "y":
get_cost()
# see if the user wants to continue
choice = input("Again? (y/n): ")
print()
print("Thanks, bye!")
if __name__ == "__main__":
main() I get that there is an error in line 13 but I don't understand where it is or how to fix it.
The error code is
File "c:\Users\Student\Downloads\Project 4_401.py", line 35, in <module> main() File "c:\Users\Student\Downloads\Project 4_401.py", line 26, in main get_cost() File "c:\Users\Student\Downloads\Project 4_401.py", line 13, in get_cost total_cost += cost builtins.TypeError: unsupported operand type(s) for +=: 'int' and 'str'
RE: Resolving unsupported operand type +=: 'int' and 'str' - ichabod801 - Sep-10-2019
The input function returns a string on line 8. You make that a string again with str(). But total_cost is an integer, because you set it to 0 on line 5. You can't add a string to an integer, so you get the error. You int() on line 8, rather than str(), so that cost is an integer.
RE: Resolving unsupported operand type +=: 'int' and 'str' - jedmond2 - Sep-10-2019
In order to get the output I'm looking for I need it to be able to show decimals. I'm trying to make total_cost all string so that I can round it to two decimals.
RE: Resolving unsupported operand type +=: 'int' and 'str' - ichabod801 - Sep-10-2019
Then you need to convert total_cost back to a string after it is fully calculated. You cannot do mathematical calculations with strings, you need ints or floats.
Have you covered the format method of strings, or f-strings, in your class? Those would be the preferred method for rounding to two decimals. Doing it manually after converting to a string is overly complicated, and rule #1 is keep it simple.
RE: Resolving unsupported operand type +=: 'int' and 'str' - jedmond2 - Sep-10-2019
Thank you for the assistance! Here is the correct code
#!/usr/bin/env python3
def get_cost():
total_cost = 0
print("ENTER ITEMS (ENTER 0 TO END)")
while True:
cost = float(input("Cost of item: "))
if cost == 0:
print_cost (total_cost)
break
else:
total_cost += cost
def print_cost(total_cost):
print("Total:\t\t " + str(round(total_cost,2)))
print("Sales tax:\t " + str(round(total_cost * .06,2)))
print("Total after tax: " + str(round(total_cost + (total_cost * .06),2)))
print()
def main():
print("Sales Tax Calculator")
print()
choice = "y"
while choice.lower() == "y":
get_cost()
# see if the user wants to continue
choice = input("Again? (y/n): ")
print()
print("Thanks, bye!")
if __name__ == "__main__":
main()