Calculator using python

Aim

Create a simple desktop calculator using python with only 5 basic arithmetic operations.

5 basic arithmetic operations are:

Addition '+'

Subtraction '-'

Multiplication '*'

Division '/'

Modulus '%'

Algorithm

Start
Take input from the user for the first number
Take input from the user for the second number
Take input from the user for the operation
- Validate the operation input
- If the operation is not one of the 5 basic arithmetic operations, print "Invalid operation" and continue
- else, go to step 5
Perform the operation
- If the operation is '+', add the two numbers.
- If the operation is '-', subtract the two numbers.
- If the operation is '*', multiply the two numbers.
- If the operation is '/', divide the two numbers.
- If the operation is '%', find the modulus of the two numbers.
Print the result
End

Program

calculator.py

# Function to add two numbers
def add(x, y):
    return x + y
 
# Function to subtract two numbers
def subtract(x, y):
    return x - y
 
# Function to multiply two numbers
def multiply(x, y):
    return x * y
 
# Function to divide two numbers
def divide(x, y):
    return x / y
 
# Function to find the modulus of two numbers
def modulus(x, y):
    return x % y
 
# Take input from the user
input1 = input("Enter the first number: \n")
input2 = input("Enter the second number: \n")
 
# Convert the input number to floating point number
num1 = float(input1)
num2 = float(input2)
 
while(True):
 
        # Take input from the user for the operation
        operation = input("Enter the operation (+, -, *, /, %) \nor press e to exit the program: \n")
 
        #validate the operation input
        if operation.lower() == 'e':
                break
        elif operation not in ['+', '-', '*', '/', '%']:
                print("Invalid operation")
                continue
        else:
                # declare a variable to store the result and initialize it to 0 (not necessary)
                result = 0
 
                # Perform the operation
                if operation == '+':
                        result = add(num1, num2)
                elif operation == '-':
                        result = subtract(num1, num2)
                elif operation == '*':
                        result = multiply(num1, num2)
                elif operation == '/':
                        result = divide(num1, num2)
                elif operation == '%':
                        result = modulus(num1, num2)
 
                # Print the result
                print(f"{num1} {operation} {num2} = {result}")

Sample Input/Output

Enter the first number:
10
Enter the second number:
5
Enter the operation (+, -, *, /, %)
or press e to exit the program:
+
10.0 + 5.0 = 15.0
Enter the operation (+, -, *, /, %)
or press e to exit the program:
-
10.0 - 5.0 = 5.0
Enter the operation (+, -, *, /, %)
or press e to exit the program:
*
10.0 * 5.0 = 50.0
Enter the operation (+, -, *, /, %)
or press e to exit the program:
/
10.0 / 5.0 = 2.0
Enter the operation (+, -, *, /, %)
or press e to exit the program:
%
10.0 % 5.0 = 0.0
Enter the operation (+, -, *, /, %)
or press e to exit the program:
e

Explanation

The program takes two numbers as input from the user.
It then takes the operation as input from the user.
If the operation is one of the 5 basic arithmetic operations, it performs the operation and prints the result.
If the operation is not one of the 5 basic arithmetic operations, it prints "Invalid operation" and continues.
The program continues to take input for the operation until the user exits the program by pressing 'e'.

Complexity Analysis

The time complexity of the program is O(1) as the program performs a fixed number of operations irrespective of the input size.

The space complexity of the program is also O(1) as the program uses a fixed amount of space to store variables and does not depend on the input size.

How can you improve this program?

You can add more arithmetic operations like exponentiation, square root, etc.
You can add input validation to ensure that the user enters valid numbers.
You can add error handling to handle division by zero or other invalid operations.
You can add a loop to allow the user to perform multiple operations without restarting the program.

Summary

In this tutorial, we learned how to create a simple desktop calculator using python with 5 basic arithmetic operations. We also discussed the algorithm, program, and sample input/output for the calculator.

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