calculator.py

import sys
print ("\nBasic Calculator Program : ")

def addition(a,b):
    return a+b
def subtraction(a,b):
    return a-b
def multiplication(a,b):
    return a*b
def division(a,b):
    return a/b
def modulus(a,b):
    return a%b


control = True
while control:
    
    print("\n1. Addition")
    print("2. Subtraction")
    print("3. Multiplication")
    print("4. Division")
    print("5. Modulus")
    print("6. Quit the program\n")
    choice = int (input("Enter your choice: "))
    
    #Cases
    if choice==1:
        
        try:
            first_number = input("\nFirst Number : ")
            if '.' in first_number:
                first_number = float(first_number)
            else:
                first_number = int(first_number)
        except ValueError:
            print("Error: Invalid Input")
            sys.exit(1)
            
        try:
            second_number = input("Second Number : ")
            if '.' in second_number:
                second_number = float(second_number)
            else:
                second_number = int (second_number)
        except ValueError:
            print("Error: Invalid Input")
            sys.exit(1)
        
        print(addition(first_number,second_number))
        print("\n")
    if choice==2:
        
        try:
            first_number = input("\nFirst Number : ")
            if '.' in first_number:
                first_number = float(first_number)
            else:
                first_number = int(first_number)
        except ValueError:
            print("Error: Invalid Input")
            sys.exit(1)
            
        try:
            second_number = input("Second Number : ")
            if '.' in second_number:
                second_number = float(second_number)
            else:
                second_number = int (second_number)
        except ValueError:
            print("Error: Invalid Input")
            sys.exit(1)
        
        print(subtraction(first_number,second_number))
        print("\n")
    if choice==3:
        
        try:
            first_number = input("\nFirst Number : ")
            if '.' in first_number:
                first_number = float(first_number)
            else:
                first_number = int(first_number)
        except ValueError:
            print("Error: Invalid Input")
            sys.exit(1)
            
        try:
            second_number = input("Second Number : ")
            if '.' in second_number:
                second_number = float(second_number)
            else:
                second_number = int (second_number)
        except ValueError:
            print("Error: Invalid Input")
            sys.exit(1)
        
        print(multiplication(first_number,second_number))
        print("\n")
    if choice==4:
        
        try:
            first_number = input("\nFirst Number : ")
            if '.' in first_number:
                first_number = float(first_number)
            else:
                first_number = int(first_number)
        except ValueError:
            print("Error: Invalid Input")
            sys.exit(1)
            
        try:
            second_number = input("Second Number : ")
            if '.' in second_number:
                second_number = float(second_number)
            else:
                second_number = int (second_number)
        except ValueError:
            print("Error: Invalid Input")
            sys.exit(1)
        
        try:
            print(division(first_number,second_number))
        except ZeroDivisionError:
            print("Cannot divide by zero")  
            #No sys.exit(1) for division , let user do other mathematical operations or do division after validating input values      
        print("\n")
   
    if choice==5:
        
        try:
            first_number = input("\nFirst Number : ")
            if '.' in first_number:
                first_number = float(first_number)
            else:
                first_number = int(first_number)
        except ValueError:
            print("Error: Invalid Input")
            sys.exit(1)
            
        try:
            second_number = input("Second Number : ")
            if '.' in second_number:
                second_number = float(second_number)
            else:
                second_number = int (second_number)
        except ValueError:
            print("Error: Invalid Input")
            sys.exit(1)
        
        print(modulus(first_number,second_number))
        print("\n")
   
    if choice==6:
        control = False
        print("Quiting the program\n")