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How do I write a calculator in python? [duplicate]

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I'm new to Python. I tried to make a basic calculator, but i can't really find the problem. It returns with 0 exit code, but nothing appears, no input no nothing. Any help with this will greatly be appreciated. Thank You.
def add(num1, num2):
return num1 + num2
def subtract(num1, num2):
return num1 - num2
def div(num1, num2):
return num1/num2
def multi(num1,num2):
return num1*num2
def main():
operation = input("What do you want to do?(+, -, *, or /):")
if (operation != "+" and operation != "-" and operation != "*" and operation != "/"):
print("Your input is invalid. Please enter a valid input.")
else:
num1 = float(input("Enter value for num1: "))
num2 = float(input("Enter value for num2: "))
if (operation == "+"):
print(add(num1, num2))
elif (operation == "-"):
print(subtract(num1, num2))
elif (operation == "*"):
print(multi(num1,num2))
elif (operation == "/"):
print(div(num1,num2))
main()

Based on the code above, you are never actually running main(). Right now, you have said that the definition of main is to prompt the user, check if the input was correct, and then do the math. The main() at the end causes the program to repeat after doing all this (not sure if you want the loop or not).
If you don't want the loop, and just want to run the calculator once, just remove the indent of the last main(), because right now the indentation means it is inside of def main(). Just move it to the left to be at the same indentation level as the def main(): and your program should run fine.

I think you are missing:
if __name__ == "__main__":
main()
Your call to main() inside main itself won't execute and that's probably why you aren't getting any input.
Other than that your code should work as expected (make sure you don't divide by zero ;) ).
Edit: to make my answer more obvious, you should have done:
def main():
operation = input("What do you want to do?(+, -, *, or /):")
if (operation != "+" and operation != "-" and operation != "*" and operation != "/"):
print("Your input is invalid. Please enter a valid input.")
else:
num1 = float(input("Enter value for num1: "))
num2 = float(input("Enter value for num2: "))
if (operation == "+"):
print(add(num1, num2))
elif (operation == "-"):
print(subtract(num1, num2))
elif (operation == "*"):
print(multi(num1,num2))
elif (operation == "/"):
print(div(num1,num2))
if __name__ == "__main__":
main()

num1=float(input("enter the first number :"))
op = input("sellect the operation :")
num2 = float(input("enter the second number :"))
if op== "+" :
print(num1+num2)
elif op == "-":
print(num1 - num2)
elif op == "*":
print(num1*num2)
elif op == "/":
print(num1 / num2)
else:
print("please enter a real operation ")
#this one is more simple

Basic Calculator:
Method 1:
# This function adds two numbers
def add(x, y):
return x + y
# This function subtracts two numbers
def subtract(x, y):
return x - y
# This function multiplies two numbers
def multiply(x, y):
return x * y
# This function divides two numbers
def divide(x, y):
return x / y
print("Select operation.")
print("1.Add")
print("2.Subtract")
print("3.Multiply")
print("4.Divide")
# Take input from the user
choice = input("Enter choice(1/2/3/4): ")
num1 = float(input("Enter first number (Should be in numeric form): "))
num2 = float(input("Enter second number (Should be in numeric form): "))
if choice == '1':
print(num1,"+",num2,"=", add(num1,num2))
elif choice == '2':
print(num1,"-",num2,"=", subtract(num1,num2))
elif choice == '3':
print(num1,"*",num2,"=", multiply(num1,num2))
elif choice == '4':
print(num1,"/",num2,"=", divide(num1,num2))
else:
print("Invalid input")
Method 2:
print("Select operation.")
print("1.Add")
print("2.Subtract")
print("3.Multiply")
print("4.Divide")
# Take input from the user
choice = input("Enter choice(1/2/3/4): ")
num1 = float(input("Enter first number (Should be in numeric form): "))
num2 = float(input("Enter second number (Should be in numeric form): "))
if choice == '1':
print(num1,"+",num2,"=", num1+num2)
elif choice == '2':
print(num1,"-",num2,"=", num1-num2)
elif choice == '3':
print(num1,"*",num2,"=", num1*num2)
elif choice == '4':
print(num1,"/",num2,"=", num1/num2)
else:
print("Invalid input")
Happy Learning...:)

How to make a calculator in Python 3

I need to create a calculator in Python that can perform all of these tasks. I have gotten this far with my code to do addition, subtraction, multiplication, and division. Can someone show me what to add to my code to add log, power, Pythagorean theorem, and factorial to my calculator? These are all the requirements for my calculator below.
Each mathematic operation needs to be its own function/method:
Addition - Takes up to 5 arguments,
Subtraction - - Takes 3 arguments,
Multiplication - Takes 4 arguments,
Division - Takes 2 arguments,
Log - Takes 1 argument,
Raise a number to a power ex. X squared,
Solve Pythagorean theorem,
Factorial
def calculate():
operation = input('''
Please type in the math operation you would like to complete:
+ for addition
- for subtraction
* for multiplication
/ for division
''')
number_1 = int(input('Please enter the first number: '))
number_2 = int(input('Please enter the second number: '))
if operation == '+':
print('{} + {} = '.format(number_1, number_2))
print(number_1 + number_2)
elif operation == '-':
print('{} - {} = '.format(number_1, number_2))
print(number_1 - number_2)
elif operation == '*':
print('{} * {} = '.format(number_1, number_2))
print(number_1 * number_2)
elif operation == '/':
print('{} / {} = '.format(number_1, number_2))
print(number_1 / number_2)
else:
print('You have not typed a valid operator, please run the program again.')
# Add again() function to calculate() function
again()
def again():
calc_again = input('''
Do you want to calculate again?
Please type Y for YES or N for NO.
''')
if calc_again.upper() == 'Y':
calculate()
elif calc_again.upper() == 'N':
print('See you later.')
else:
again()
calculate()

It's just the ideas of your requested functions. I added some of them to your calculator. You can also change the hints that you want to show to the user.
PS: Better to use while for the calculator loop.
import math
def calculate():
operation = input('''
Please type in the math operation you would like to complete:
+ for addition
- for subtraction
* for multiplication
/ for division
! for factorial
log for logarithm(number, base)
hypot for Pythagorean
''')
number_1 = int(input('Please enter the first number: '))
number_2 = int(input('Please enter the second number: '))
if operation == '+':
print('{} + {} = '.format(number_1, number_2))
print(number_1 + number_2)
elif operation == '-':
print('{} - {} = '.format(number_1, number_2))
print(number_1 - number_2)
elif operation == '*':
print('{} * {} = '.format(number_1, number_2))
print(number_1 * number_2)
elif operation == '/':
print('{} / {} = '.format(number_1, number_2))
print(number_1 / number_2)
elif operation == '!':
print(math.factorial(number_1))
print(math.factorial(number_2))
elif operation == 'log':
print(math.log(number_1, number_2))
elif operation == 'hypot':
print(math.hypot(number_1, number_2))
else:
print('You have not typed a valid operator, please run the program again.')
# Add again() function to calculate() function
again()
def again():
calc_again = input('''
Do you want to calculate again?
Please type Y for YES or N for NO.
''')
if calc_again.upper() == 'Y':
calculate()
elif calc_again.upper() == 'N':
print('See you later.')
else:
again()
calculate()
I updated the answer based on the comment; you want to take a variable number of inputs from a user like n numbers. I used add() for your situation to answer your exact issue and removed additional codes.
def add(numbers_list):
return sum(numbers_list)
if __name__ == "__main__":
while(True):
number_of_inputs = int(input('Number of inputs? '))
numbers = [float(input(f'Please enter a number({i + 1}): ')) for i in range(number_of_inputs)]
print(add(numbers))

How to break a while loop in python?

Here I m making a small calculator. accepting two numbers and one operator this will be easy while I'm using function but in this I'm using the while condition statement but there is a error it will not breaking while every operation it will ask to user that it will want to any operation again in 'Y' for yes and 'N' for no but There is an error it will not changing the value of n. Below is my program:
n = 1
def again(number):
print('value of n in again fucntion', n)
calc_again = input('''
Do you want to calculate again?
Please type Y for YES or N for NO.
''')
if calc_again.upper() == 'Y':
number = 1
return number
elif calc_again.upper() == 'N':
number = 0
print('value of n after say no', number)
return number
else:
again(n)
while n > 0:
print('while n value', n)
operation = input('''
Please type in the math operation you would like to complete:
+ for addition
- for subtraction
* for multiplication
/ for division
''')
number_1 = int(input('Please enter the first number: '))
number_2 = int(input('Please enter the second number: '))
if operation == '+':
print('{} + {} = '.format(number_1, number_2))
print(number_1 + number_2)
again(n)
elif operation == '-':
print('{} - {} = '.format(number_1, number_2))
print(number_1 - number_2)
again(n)
elif operation == '*':
print('{} * {} = '.format(number_1, number_2))
print(number_1 * number_2)
again(n)
elif operation == '/':
print('{} / {} = '.format(number_1, number_2))
print(number_1 / number_2)
again(n)
else:
print('You have not typed a valid operator, please run the program again.')
Can anybody please help me for solving this. Thanks in advance.

You use the local variable number in again, but use n outside. You have to assign the return value of again to n.
def again():
while True:
calc_again = input('''
Do you want to calculate again?
Please type Y for YES or N for NO.
''')
if calc_again.upper() == 'Y':
number = 1
return number
elif calc_again.upper() == 'N':
number = 0
print('value of n after say no', number)
return number
n = 1
while n > 0:
print('while n value', n)
operation = input('''
Please type in the math operation you would like to complete:
+ for addition
- for subtraction
* for multiplication
/ for division
''')
number_1 = int(input('Please enter the first number: '))
number_2 = int(input('Please enter the second number: '))
if operation == '+':
print('{} + {} = '.format(number_1, number_2))
print(number_1 + number_2)
elif operation == '-':
print('{} - {} = '.format(number_1, number_2))
print(number_1 - number_2)
elif operation == '*':
print('{} * {} = '.format(number_1, number_2))
print(number_1 * number_2)
elif operation == '/':
print('{} / {} = '.format(number_1, number_2))
print(number_1 / number_2)
else:
print('You have not typed a valid operator, please run the program again.')
n = again()

If you want to break your loop, then simply use break where you want the loop to stop.
Edit:
Your loop can be like:
while n > 0:
print('while n value', n)
operation = input('''
Please type in the math operation you would like to complete:
+ for addition
- for subtraction
* for multiplication
/ for division
''')
number_1 = int(input('Please enter the first number: '))
number_2 = int(input('Please enter the second number: '))
if operation == '+':
print('{} + {} = '.format(number_1, number_2))
print(number_1 + number_2)
if again(n) == 0:break
elif operation == '-':
print('{} - {} = '.format(number_1, number_2))
print(number_1 - number_2)
if again(n) == 0:break
elif operation == '*':
print('{} * {} = '.format(number_1, number_2))
print(number_1 * number_2)
if again(n) == 0:break
elif operation == '/':
print('{} / {} = '.format(number_1, number_2))
print(number_1 / number_2)
if again(n) == 0:break
else:
print('You have not typed a valid operator, please run the program again.')

There is no need to store a value n
Change the while loop to while True:
Change the again function to return a Boolean.
use the following syntax when calling the again function.
if not again():
break
There is no need to store a value n
Change the while loop to while True:
Change the again function to return a Boolean.
use the following syntax when calling the again function.
if not again():
break
The final code will be something like this.
def again():
calc_again = input('''
Do you want to calculate again?
Please type Y for YES or N for NO.
''')
if calc_again.upper() == 'Y':
return True
elif calc_again.upper() == 'N':
return False
else:
return again()
while True:
operation = input('''
Please type in the math operation you would like to complete:
+ for addition
- for subtraction
* for multiplication
/ for division
''')
number_1 = int(input('Please enter the first number: '))
number_2 = int(input('Please enter the second number: '))
if operation == '+':
print('{} + {} = '.format(number_1, number_2))
print(number_1 + number_2)
elif operation == '-':
print('{} - {} = '.format(number_1, number_2))
print(number_1 - number_2)
elif operation == '*':
print('{} * {} = '.format(number_1, number_2))
print(number_1 * number_2)
elif operation == '/':
print('{} / {} = '.format(number_1, number_2))
print(number_1 / number_2)
else:
print('You have not typed a valid operator, please run the program again.')
break
if not again():
break

You can simplify your code as follow, and to avoid unnecessary recursion in the code:
operations = {
"+": lambda x, y: x + y,
"-": lambda x, y: x - y,
"/": lambda x, y: x / y,
"*": lambda x, y: x * y
}
continue_calculation = ""
while True:
calc_again = input('''Do you want to calculate again?Please type Y for YES or N for NO.''')
if calc_again == "n" or calc_again == "N":
break
operation = input('''Please type in the math operation you would like to complete:
+ for addition
- for subtraction
* for multiplication
/ for division
''')
number_1 = int(input('Please enter the first number: '))
number_2 = int(input('Please enter the second number: '))
try:
print(operations[operation](number_1, number_2))
except:
print('You have not typed a valid operator, please run the program again.')

What does getting a string index out of range error mean?

I am making a calculator in python 3, and I made a function to check for letters in the input. When it runs the letter check though, it gives me an error of string index out of range. Here is the code:
while True:
num = ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z']
op = input("What operation would you like to use(+,-,*,/,**): ")
num1 = input("What is the first number you want to use: ")
length1 = len(num1)
lc1 = 0
def letterCheck1():
global num1
global length1
global lc1
while lc1 <= length1:
if num1[lc1] in num:
num1 = input("No letters, just numbers: ")
else:
lc1 = lc1 + 1
while True:
letterCheck1()
if len(num1) == 0:
num1 = input("Actually enter something: ")
continue
else:
break
num2 = input ("What is the second number you want to use: ")
length2 = len(num2)
lc2 = 0
def letterCheck2():
global num2
global length2
global lc2
while lc2 <= length2:
if num2[lc2] in num:
num2 = input("No letters, just numbers: ")
else:
lc2 = lc2 + 1
while True:
while True:
if op == "/" and num2 == "0":
num2 = input("It is impossible to divide a number by 0. Try again: ")
continue
else:
break
letterCheck2()
if len(num2) == 0:
num2 = input("Enter more than 0 numbers please: ")
continue
else:
break
if op == "+":
print (float(num1) + float(num2))
elif op == "-":
print (float(num1) - float(num2))
elif op == "*":
print (float(num1) * float(num2))
elif op == "/":
print (float(num1) / float(num2))
elif op == "**":
print (float(num1) ** float(num2))
again = input("Would you like to do another problem? 1(Yes), 2(No): ")
while True:
if again != "1" or again != "2":
again = input("Please enter 1(Yes), or 2(No): ")
continue
else:
break
if again == "1":
continue
elif again == "2":
leave = input("You are about to exit, do you want to continue? 1(Yes), 2(No): ")
while True:
if leave != ("1" or "2"):
leave = input("Please enter 1(Yes), or 2(No): ")
continue
else:
break
if leave == '1':
continue
elif leave == '2':
break

Indexing from 0 to len(num1) - 1. Fix this
while lc1 < length1
and this
while lc2 < length2

Here is a much cleaner way to do it:
def get_float(prompt):
while True:
try:
return float(input(prompt))
except ValueError:
# not a float, try again
pass
# division is the only operation that requires more than a one-liner
def op_div(a, b):
if b == 0:
print("Dividing by 0 makes the universe explode. Don't do that!")
return None
else:
return a / b
# dispatch table - look up a string to get the corresponding function
ops = {
'*': lambda a,b: a * b,
'/': op_div,
'+': lambda a,b: a + b,
'-': lambda a,b: a - b,
'**': lambda a,b: a ** b
}
def main():
while True:
op = input("What operation would you like to use? [+, -, *, /, **, q to quit] ").strip().lower()
if op == "q":
print("Goodbye!")
break
elif op not in ops:
print("I don't know that operation")
else:
a = get_float("Enter the first number: ")
b = get_float("Enter the second number: ")
res = ops[op](a, b)
print("{} {} {} = {}".format(a, op, b, res))
if __name__=="__main__":
main()

Basic Calculator in Python [closed]

Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 2 years ago.
Improve this question
I'm new to Python. I tried to make a basic calculator, but i can't really find the problem. It returns with 0 exit code, but nothing appears, no input no nothing. Any help with this will greatly be appreciated. Thank You.
def add(num1, num2):
return num1 + num2
def subtract(num1, num2):
return num1 - num2
def div(num1, num2):
return num1/num2
def multi(num1,num2):
return num1*num2
def main():
operation = input("What do you want to do?(+, -, *, or /):")
if (operation != "+" and operation != "-" and operation != "*" and operation != "/"):
print("Your input is invalid. Please enter a valid input.")
else:
num1 = float(input("Enter value for num1: "))
num2 = float(input("Enter value for num2: "))
if (operation == "+"):
print(add(num1, num2))
elif (operation == "-"):
print(subtract(num1, num2))
elif (operation == "*"):
print(multi(num1,num2))
elif (operation == "/"):
print(div(num1,num2))
main()

Based on the code above, you are never actually running main(). Right now, you have said that the definition of main is to prompt the user, check if the input was correct, and then do the math. The main() at the end causes the program to repeat after doing all this (not sure if you want the loop or not).
If you don't want the loop, and just want to run the calculator once, just remove the indent of the last main(), because right now the indentation means it is inside of def main(). Just move it to the left to be at the same indentation level as the def main(): and your program should run fine.

I think you are missing:
if __name__ == "__main__":
main()
Your call to main() inside main itself won't execute and that's probably why you aren't getting any input.
Other than that your code should work as expected (make sure you don't divide by zero ;) ).
Edit: to make my answer more obvious, you should have done:
def main():
operation = input("What do you want to do?(+, -, *, or /):")
if (operation != "+" and operation != "-" and operation != "*" and operation != "/"):
print("Your input is invalid. Please enter a valid input.")
else:
num1 = float(input("Enter value for num1: "))
num2 = float(input("Enter value for num2: "))
if (operation == "+"):
print(add(num1, num2))
elif (operation == "-"):
print(subtract(num1, num2))
elif (operation == "*"):
print(multi(num1,num2))
elif (operation == "/"):
print(div(num1,num2))
if __name__ == "__main__":
main()

num1=float(input("enter the first number :"))
op = input("sellect the operation :")
num2 = float(input("enter the second number :"))
if op== "+" :
print(num1+num2)
elif op == "-":
print(num1 - num2)
elif op == "*":
print(num1*num2)
elif op == "/":
print(num1 / num2)
else:
print("please enter a real operation ")
#this one is more simple

Basic Calculator:
Method 1:
# This function adds two numbers
def add(x, y):
return x + y
# This function subtracts two numbers
def subtract(x, y):
return x - y
# This function multiplies two numbers
def multiply(x, y):
return x * y
# This function divides two numbers
def divide(x, y):
return x / y
print("Select operation.")
print("1.Add")
print("2.Subtract")
print("3.Multiply")
print("4.Divide")
# Take input from the user
choice = input("Enter choice(1/2/3/4): ")
num1 = float(input("Enter first number (Should be in numeric form): "))
num2 = float(input("Enter second number (Should be in numeric form): "))
if choice == '1':
print(num1,"+",num2,"=", add(num1,num2))
elif choice == '2':
print(num1,"-",num2,"=", subtract(num1,num2))
elif choice == '3':
print(num1,"*",num2,"=", multiply(num1,num2))
elif choice == '4':
print(num1,"/",num2,"=", divide(num1,num2))
else:
print("Invalid input")
Method 2:
print("Select operation.")
print("1.Add")
print("2.Subtract")
print("3.Multiply")
print("4.Divide")
# Take input from the user
choice = input("Enter choice(1/2/3/4): ")
num1 = float(input("Enter first number (Should be in numeric form): "))
num2 = float(input("Enter second number (Should be in numeric form): "))
if choice == '1':
print(num1,"+",num2,"=", num1+num2)
elif choice == '2':
print(num1,"-",num2,"=", num1-num2)
elif choice == '3':
print(num1,"*",num2,"=", num1*num2)
elif choice == '4':
print(num1,"/",num2,"=", num1/num2)
else:
print("Invalid input")
Happy Learning...:)