Basic calculator program in Python

Question

I was writing a basic calculator program to practice my skills at python. I'm a beginner at Python and was wondering if there is a way to simplify this code of mine? It seems a little bit too long and messy in some sort of way. Again, I'm still a beginner so I don't know all the tricks in the book!

import math
import time
def add(x,y):
 return x + y
def subtract(x,y):
 return x - y
def divide(x,y):
 return x / y
def multiply(x,y):
 return x * y
def sqrt(x):
 if math.sqrt(x) * math.sqrt(x):
 return False
 else:
 return math.sqrt(x)
def power(x,y):
 return math.pow(x,y)
def repeat():
 print('Would you like to perform another calculation? y/n')
 rep = input('')
 if rep.lower() == 'y':
 time.sleep(0.5)
 main()
 elif rep.lower() == 'n':
 print('Goodbye!')
 time.sleep(1)
 exit()
 else:
 print('Please enter y/n.')
 time.sleep(1)
 repeat()
def numCheck(x):
 try:
 int(x)
 except ValueError:
 print("Please enter a valid number.")
 print('')
 time.sleep(1)
 main()
def choiceCheck(y, z):
 for x in y:
 if x == z:
 return True
 break
 else:
 pass
def main():
 choices = ['1', '2', '3', '4']
 print('Choose your operation: ')
 print('1. Add')
 print('2. Subtract')
 print('3. Divide')
 print('4. Multiply')
 print('5. Square Root')
 print('6. Exponent')
 print('1/2/3/4/5/6')
 choice = input('')
 if choice == '5':
 print('Please choose the number you would like to square root.')
 rt = input('')
 numCheck(rt)
 rt = int(rt)
 rts = sqrt(rt)
 if rts == False:
 print('%d is an irrational number.' % (rt))
 else:
 print('The square root of %d is %d' % (rt, rts))
 repeat() 
 elif choice == '6': 
 print('Choose the number you would like to raise to a power: ')
 base = input('')
 numCheck(base)
 base = int(base)
 print('')
 print('Now please choose the indice: ')
 ind = input('')
 numCheck(ind)
 ind = int(ind)
 time.sleep(1)
 print('%d to the power of %d is %d' % (base, ind, power(base,ind)))
 repeat()
 elif choiceCheck(choices, choice) != True: 
 print('Please choose a valid number.')
 print('')
 time.sleep(1)
 main()
 a = input('Please choose your first number: ')
 numCheck(a)
 a = int(a)
 print('')
 b = input('Please choose your second number: ')
 numCheck(b)
 b = int(b)
 if choice == '1':
 print('%d + %d = %d' % (a, b, add(a,b)))
 elif choice == '2':
 print('%d - %d = %d' % (a, b, subtract(a,b)))
 elif choice == '3':
 print('%r / %r = %r' % (a, b, divide(a,b)))
 elif choice == '4':
 print('%d * %d = %d' % (a, b, multiply(a,b)))
 else:
 print('Please choose a valid number')
 print('')
 time.sleep(1)
 main()
 repeat()
main()

All help is appreciated!

• Mahmood Muhammad Nageeb: I don't get if math.sqrt(x) * math.sqrt(x): return False. What is it for?
• Jean-François Fabre: should probably be if x<0 return False. And there's a lot of useless recursion on main.

Answer 1

This being Python, where indentation is significant, it is important to consistently follow the convention of four spaces per level.

You shouldn't format the square root as %d, since the result is rarely an integer.

There are several recommendations that I could make about organizing this code, but the single most important point is that functions should not be treated as goto labels. If you need a loop, then write a loop using while or for. Don't have main call main(). Don't have repeat call main(). Don't have repeat call repeat(). Otherwise, you end up with spaghetti code.