Making a calculator

When playing with numbers, a calculator is always needed. Why not make one myself?

There are many ways to make a calculator but I used newfound knowledge of dictionaries to make this calculator.

Making process

To reduce the amount of code I would need to write, I made functions for each arithmetic operation.

def add(n1, n2):

    return n1 + n2

def subtract(n1, n2):

    return n1-n2

def multiply(n1,n2):

    return n1 *n2

def divide(n1,n2):

    return n1/n2

After, I used dictionaries to store the newly made functions. This is a new skill I learned:

def add(n1, n2):

    return n1+n2

my_fav = add

print(my_fav(2,3))

So I implemented this in the same way:

operation = {

    '+': add,

    '-':subtract,

    '*':multiply,

    '/':divide

}

The next thing I needed to do was actually make the calculator function with the new functions I had made.

I learned through this project that I didn't need to add arguments to new functions. I could simply make it so that I could call for an input and implement it later on in the function.

I wanted to make sure the user could either continue with their calculation or start a wholly new calculation. So I wanted to use the while loop. However my big error was that I used two while loops for each instance I wanted the the user to be able to experience. At first the code worked well but it suddenly stopped working at a certain point.( I am still not entirely sure why this is)

value =0

while restart == 'yes':

    num1 = float(input('input first number'))

    ask_operation = input('''+

    -

    *

    /\n''')

    num2 = float(input('input second number'))

    value = operation[ask_operation](num1, num2)

    print(f'{num1} {ask_operation} {num2} = {value}')

    restart = input('do you wish to restart or continue? yes for restart no for continue:\n').lower()

while restart =='no':

    print('\n'*100)

    num3 = float(input('input second number'))

    ask_operation = input('''+

        -

        *

        /\n''')

    value = operation[ask_operation](value, num3)

    print(f'{value} {ask_operation} {num3} = {value}')

    restart = input('do you wish to restart or continue? yes for restart no for continue:\n').lower()

Eventually I rewrote the code so that it only had 1 loop. I also added the newly made calculation function in the making of the calculation function to make it into a sort of loop.

def calculator():

    should_accumulate = True

    num1 = float(input('input number:\n'))

    while should_accumulate:

        num2 = float(input('input number:\n'))

        for op in operation:

            print(op)

        selected_operation = input('select operation:\n')

        result = operation[selected_operation](num1, num2)

        print(f'{num1} {selected_operation} {num2} = {result}')

        choice = input('if you wish to continue with result type y, if you want to restart type n').lower()

        if choice == 'y':

            num1 = result

        else:

            should_accumulate = False

            print('\n'*100)

            calculator()

This was not easy to think of and many of my early ideas had faults. I realized I still have a long way to go.

The finished code looks something like this:

def add(n1, n2):

    return n1 + n2

def subtract(n1, n2):

    return n1-n2

def multiply(n1,n2):

    return n1 *n2

def divide(n1,n2):

    return n1/n2

operation = {

    '+': add,

    '-':subtract,

    '*':multiply,

    '/':divide

}

def calculator():

    should_accumulate = True

    num1 = float(input('input number:\n'))

    while should_accumulate:

        num2 = float(input('input number:\n'))

        for op in operation:

            print(op)

        selected_operation = input('select operation:\n')

        result = operation[selected_operation](num1, num2)

        print(f'{num1} {selected_operation} {num2} = {result}')

        choice = input('if you wish to continue with result type y, if you want to restart type n').lower()

        if choice == 'y':

            num1 = result

        else:

            should_accumulate = False

            print('\n'*100)

            calculator()

Other things I learned:

• fruits = {'a': 'yes', 'b':'banana'}

  print(max(fruits, key=fruits.get)

  finds maximum value if value is numeral

• for key in dict_:

      print(key)

      print(dict_[key])

  ->prints both key and value

• dict:

  for thing in dict_:

         print(thing)

  ->gives only keys not the descriptions

• dict_name ={

             'hi':'hi is a form of greeting',

             'hello': 'hello is a longer form of hi',

  }

  - indent the elements in dict

  - add comma after element

  - add last brace at the start of new line