Making a simple calculator

We’ll discover how to create a basic calculator using Python. Feel free to utilize any online Python environment to write the code. I typically use this one: https://programiz.pro/ide/python.

Python’s straightforward syntax and clear structure make it perfect for developing a calculator application. This project will provide insight into essential concepts such as user input handling, conditional statements, and fundamental arithmetic operations.

The Code

num1 = float(input("Enter first number: "))
operator = input("Enter operator (+, -, *, /): ")
num2 = float(input("Enter second number: "))

if operator == "+":
    result = num1 + num2
elif operator == "-":
    result = num1 - num2
elif operator == "*":
    result = num1 * num2
elif operator == "/":
    result = num1 / num2
else:
    result = "Invalid operator"

print("Result:", result)

Explanation

To understand this program. Let’s break it down into a few parts to understand it.

Part One: User Input

This section takes in the user input using the “input" function. The “float" function is used to convert the input into floating-point numbers, which allows for both integer and decimal inputs. The users will be asked to enter the first number, then an operator (+, -, *, /), and finally a second number.

Part Two: Conditional Statements

Lines 5 – 14 capture the conditional statements of the program. This block utilizes conditional statements to evaluate the entered operator and perform the corresponding arithmetic operation. If the operator is addition (+), the program adds the two numbers; if it’s subtraction (-), it subtracts the second number from the first, and so on. If the entered operator is not one of these, the program will set the result to say “Invalid Operator”.

if operator == "+":
- If the entered operator is addition (+), the program executes the block of code indented under this “if” statement. It calculates the sum of num1 and num2 and assigns the result to the variable result.
elif operator == "-":
- If the if statement above is not true (i.e., the operator is not +), the program checks this elif (else if) statement. If the operator is subtraction (-), it executes the corresponding block, subtracting num2 from num1 and assigning the result to result.
elif operator == "*":
- Similarly, if the previous conditions are not met, this elif statement checks whether the operator is multiplication (*). If true, it calculates the product of num1 and num2 and assigns the result to result.
elif operator == "/":
- This elif statement handles the case of division (/). If the operator is /, it performs the division of num1 by num2 and assigns the result to result.
else:
- If none of the preceding if or elif conditions are true (i.e., the entered operator is not +, -, *, or /), the program executes the else block. In this case, it sets result to “Invalid operator,” indicating that the entered operator is not recognized.

Part Three: Output

The “print” statement displays the result of the calculation to the user. If a valid operator was entered, the result is shown; otherwise, a message will return saying “Invalid Operator”.

Demonstration

Here is a quick demonstration of the program when it is executed.