Python Program to Make a Simple Calculator

Here we will be making a simple calculator in which we can perform basic arithmetic operations like addition, subtraction, multiplication, or division.

Python Program to Make a Simple Calculator

Create a simple calculator which can perform basic arithmetic operations like addition, subtraction, multiplication, or division depending upon the user input. Approach :

User chooses the desired operation. Options 1, 2, 3, and 4 are valid.
Two numbers are taken and an if…elif…else branching is used to execute a particular section.
Using functions add(), subtract(), multiply() and divide() evaluate respective operations.

Python3

# Python program for simple calculator

# Function to add two numbers
def add(num1, num2):
    return num1 + num2

# Function to subtract two numbers
def subtract(num1, num2):
    return num1 - num2

# Function to multiply two numbers
def multiply(num1, num2):
    return num1 * num2

# Function to divide two numbers
def divide(num1, num2):
    return num1 / num2

print("Please select operation -\n" \
        "1. Add\n" \
        "2. Subtract\n" \
        "3. Multiply\n" \
        "4. Divide\n")


# Take input from the user
select = int(input("Select operations form 1, 2, 3, 4 :"))

number_1 = int(input("Enter first number: "))
number_2 = int(input("Enter second number: "))

if select == 1:
    print(number_1, "+", number_2, "=",
                    add(number_1, number_2))

elif select == 2:
    print(number_1, "-", number_2, "=",
                    subtract(number_1, number_2))

elif select == 3:
    print(number_1, "*", number_2, "=",
                    multiply(number_1, number_2))

elif select == 4:
    print(number_1, "/", number_2, "=",
                    divide(number_1, number_2))
else:
    print("Invalid input")

Output:

Please select operation -
1. Add
2. Subtract
3. Multiply
4. Divide
Select operations form 1, 2, 3, 4 : 1
Enter first number : 15
Enter second number : 14
15 + 14 = 29

Python Program to Make GUI Calculator

GUI of a Calculator Which will help to add, subtract , Multiply and divide

Python

# pip install tkinter
import tkinter as tk
import tkinter.messagebox
from tkinter.constants import SUNKEN

window = tk.Tk()
window.title('Calculator-GeeksForGeeks')
frame = tk.Frame(master=window, bg="skyblue", padx=10)
frame.pack()
entry = tk.Entry(master=frame, relief=SUNKEN, borderwidth=3, width=30)
entry.grid(row=0, column=0, columnspan=3, ipady=2, pady=2)


def myclick(number):
    entry.insert(tk.END, number)


def equal():
    try:
        y = str(eval(entry.get()))
        entry.delete(0, tk.END)
        entry.insert(0, y)
    except:
        tkinter.messagebox.showinfo("Error", "Syntax Error")


def clear():
    entry.delete(0, tk.END)


button_1 = tk.Button(master=frame, text='1', padx=15,
                     pady=5, width=3, command=lambda: myclick(1))
button_1.grid(row=1, column=0, pady=2)
button_2 = tk.Button(master=frame, text='2', padx=15,
                     pady=5, width=3, command=lambda: myclick(2))
button_2.grid(row=1, column=1, pady=2)
button_3 = tk.Button(master=frame, text='3', padx=15,
                     pady=5, width=3, command=lambda: myclick(3))
button_3.grid(row=1, column=2, pady=2)
button_4 = tk.Button(master=frame, text='4', padx=15,
                     pady=5, width=3, command=lambda: myclick(4))
button_4.grid(row=2, column=0, pady=2)
button_5 = tk.Button(master=frame, text='5', padx=15,
                     pady=5, width=3, command=lambda: myclick(5))
button_5.grid(row=2, column=1, pady=2)
button_6 = tk.Button(master=frame, text='6', padx=15,
                     pady=5, width=3, command=lambda: myclick(6))
button_6.grid(row=2, column=2, pady=2)
button_7 = tk.Button(master=frame, text='7', padx=15,
                     pady=5, width=3, command=lambda: myclick(7))
button_7.grid(row=3, column=0, pady=2)
button_8 = tk.Button(master=frame, text='8', padx=15,
                     pady=5, width=3, command=lambda: myclick(8))
button_8.grid(row=3, column=1, pady=2)
button_9 = tk.Button(master=frame, text='9', padx=15,
                     pady=5, width=3, command=lambda: myclick(9))
button_9.grid(row=3, column=2, pady=2)
button_0 = tk.Button(master=frame, text='0', padx=15,
                     pady=5, width=3, command=lambda: myclick(0))
button_0.grid(row=4, column=1, pady=2)

button_add = tk.Button(master=frame, text="+", padx=15,
                       pady=5, width=3, command=lambda: myclick('+'))
button_add.grid(row=5, column=0, pady=2)

button_subtract = tk.Button(
    master=frame, text="-", padx=15, pady=5, width=3, command=lambda: myclick('-'))
button_subtract.grid(row=5, column=1, pady=2)

button_multiply = tk.Button(
    master=frame, text="*", padx=15, pady=5, width=3, command=lambda: myclick('*'))
button_multiply.grid(row=5, column=2, pady=2)

button_div = tk.Button(master=frame, text="/", padx=15,
                       pady=5, width=3, command=lambda: myclick('/'))
button_div.grid(row=6, column=0, pady=2)

button_clear = tk.Button(master=frame, text="clear",
                         padx=15, pady=5, width=12, command=clear)
button_clear.grid(row=6, column=1, columnspan=2, pady=2)

button_equal = tk.Button(master=frame, text="=", padx=15,
                         pady=5, width=9, command=equal)
button_equal.grid(row=7, column=0, columnspan=3, pady=2)

window.mainloop()

Output:

Time complexity:
The time complexity of this calculator depends on the number of operations involved in the calculation. The basic operations such as addition, subtraction, multiplication and division take O(1) time complexity. For more complex calculations involving multiple operations, the time complexity will be higher.

Space complexity:
The space complexity of this calculator is O(1). This is because the calculator only needs to store the user input and the result of the calculation which can be done in a fixed amount of memory.