Calculator Program In Python - Explained With Code Examples

0 min read

Python is a versatile programming language known for its simplicity and readability, making it ideal for a wide range of applications from web development to scientific computing. Learning Python opens up a world of possibilities for programmers, and creating a fully functional calculator program in Python is a great way to get started. In this article, we will do just that. You will learn how to write a Python program that can be used as a simple calculator.

Let's first understand the fundamental function of a calculator in computing, a tool that goes beyond simple arithmetic, before diving into the calculator code.

Why Build A Calculator Program In Python?

For those who are new to Python programming, building a Python calculator provides an engaging and instructive experience that allows for customization and additional development as one's abilities advance. Here are some of the benefits you’ll get from building a calculator program in Python:

• Learning Programming Concepts: For novice programmers, creating a calculator in Python can be a great way to acquire the essentials of the language. It allows practice with variables, functions, and control structures like loops and conditional statements. It covers basic arithmetic operations (addition, subtraction, multiplication, and division).
• Practical Exercise: Using a calculator allows you to put your theoretical knowledge to use in a real-world project. It aids in comprehending how to use Python for computations, handle user input, and organize code.
• Customization and Improvement: After you've made a simple calculator, you can add more features to increase its usefulness. For instance, you could use libraries like Tkinter to create a graphical user interface (GUI), handle errors gracefully, implement scientific functions (trigonometry, exponentiation, and logarithms), and design an intuitive user interface.

Put your tech skills to the test! Sharpen your computer fundamentals with Unstop

Prerequisites To Writing A Calculator Program In Python

In order to develop a simple calculator in Python, you'll need to know about or check the following:

• Installation of Python: Verify that Python is installed on your computer. From the official website, python.org, you can download and install Python. Select the most recent stable version that is currently accessible. Python 2 and Python 3 can both be used to build the calculator, but Python 3 is advised due to its continuous support and enhancements.
• A text editor or Integrated Development Environment (IDE): To write and run Python code, you'll need a coding environment. You can use IDEs such as VSCode, PyCharm, or Python IDLE (the built-in IDE for Python). Alternatively, all you need to write Python code is a basic text editor such as Notepad++, Atom, or Sublime Text.
• Basic Syntax Understanding: Become acquainted with the syntax, variables, data types, operators, control structures (loops, if statements), and functions of Python. To help you understand these ideas, there are online tutorials, documentation, and learning resources for Python available.
• Handling Input/Output: Recognize how to use Python to manage input from users and display output. Users can provide input using the input() function, and output can be shown on the console using the print() function.

Approach For Writing A Calculator Program In Python

Writing a calculator program in Python generally entails the following steps:

• Recognize requirements: Clearly define the features that the calculator must have. Select the basic arithmetic operations (multiplication, division, addition, and subtraction) that the calculator will execute. It's also possible to think about adding features like exponentiation, square root, trigonometric functions, etc.
• Create the Program Structure: Make a plan for your program's structure. Choose the functions, variables, and control flow that you will require. To keep your code organized, you could, for example, write different functions for each arithmetic operation.
• Gather User Input: To gather user input, use Python's input() function. Request that the user input the desired operation and a number.
• Carry Out Calculations: Using Python's built-in arithmetic operators (+, -, *, /), carry out the necessary arithmetic operation based on the user's input. Make sure to gracefully handle situations such as division by zero or invalid inputs.
• Present the Result: After the computation is finished, use Python's print() function to present the result to the user.
• Add More Functionalities (Optional): If you'd like, you can incorporate additional features like managing decimals, carrying out scientific computations, or designing an intuitive user interface (graphical or command-line).
• Error Handling: Use error handling to deal with unforeseen inputs and potential calculation errors. Try and except blocks can be used to catch exceptions and show informative error messages.

Simple Calculator Program In Python

We'll be breaking down the process of writing the Python calculator program into easy steps. To aid in a thorough understanding of the concepts, a basic calculator program in Python that can carry out addition, subtraction, multiplication, and division—all of which depend on the input provided by the user—should be created.

Step 1: Create a File for the Calculator

To begin writing a calculator program in Python, we first need to create a file. The method to get this done is given below.

Method Description:

• Creating a Python File: Open a text editor or an IDE and create a new file with a ".py" extension. For example, name it calculator.py.
• Write Python Code: Inside the file, start writing Python code to build the calculator.

Code Example (calculator.py):

# Simple Calculator Program in Python

# 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):
    if y == 0:
        return "Cannot divide by zero"
    return x / y

# Display operations to the user
print("Select operation:")
print("1. Add")
print("2. Subtract")
print("3. Multiply")
print("4. Divide")

Step 2: Prompt for User Input

The next step is to prompt the user to provide us with valid input. The method for the same and an example code is given below.

Method Description:

• Use input() Function: Prompt the user to select an operation and enter numbers for calculation.
• Assign Inputs to Variables: Read user input and assign the input values to variables.

Code Example (continuation in calculator.py):

# Get user input for operation choice
choice = input("Enter choice (1/2/3/4): ")

# Get user input for numbers
num1 = float(input("Enter first number: "))
num2 = float(input("Enter second number: "))

Step 3: Put Calculation Logic & Implement Conditional Statements

The user is prompted to select an operation for further calculation. The method for the same and an example code is given below.

Method Description:

• Once the user submits the input, we use the if-elif statement to execute the respective function.
• In addition to the four options, we also have an else block, in case the user inputs irrelevant data.
• We pass the variables input by the user into the function. The statement thus returns the outcome of the operations.

Code Example (continuation in calculator.py):

# Based on the user's choice, perform the arithmetic operations

if choice == '1':
    result = num1 + num2
elif choice == '2':
    result = num1 - num2
elif choice == '3':
    result = num1 * num2
elif choice == '4':
    if num2 == 0:
        result = "Cannot divide by zero"
    else:
        result = num1 / num2
else:
 result = "Invalid input"

Step 4: Check & Print the Output

In this step, conditional statements are used to analyse if the outcome is a valid result of calculations, or something went wrong.

Method Description:

• We use an if-else statement with equality relational operator and OR logical operator. Here we check if the outcome is either 'Invalid Input' or 'Cannot Divide by zero'
• If this condition is true, then we display the same message. If false, then we display the actual outcome of the calculation.

Code Example (continuation in calculator.py):

# Provide feedback for invalid input
if result == "Invalid input" or result == "Cannot divide by zero":
    print(result)
else:
    print("Result:", result)

Now that we know the different segments of how to write the calculator program in Python language, let's take a look at a complete example. It will help you understand how all of the components discussed above come into play. 

Calculator Program In Python Using Functions

For using functions to encapsulate arithmetic operations (addition, subtraction, multiplication, and division), the method entails writing a Python calculator program. Functions facilitate the modularization of the code, improving its organization, readability, and reusability.

General approach followed in coding a calculator using functions:

• Define Functions: For every arithmetic operation (addition, subtraction, multiplication, and division), create a distinct function.
• Display Operations: Inform the user of the available arithmetic operations.
• Accept User Input: Ask the user to select an action and enter a number.
• Carry Out Calculations: Select the appropriate function and call it to carry out the calculation.
• Display Result: Show the user the computation's outcome.

Now, let's code this to get a better understanding of the given approach:

Code Example: 

Output:

Select operation:
1. Add
2. Subtract
3. Multiply
4. Divide
Enter choice (1/2/3/4): 3
Enter first number: 4
Enter second number: 5
Result: 20.0

The user is prompted to choose an operation and enter numbers when the code runs. Once the options and numbers have been entered, the code executes the selected action and shows the outcome or the relevant error message in the event that the input is incorrect.

Explanation:

1. The code begins by defining four functions, each representing a basic arithmetic operation, i.e., add(x, y), subtract(x, y), multiply(x, y), and divide(x, y).

2. Each function uses the respective arithmetic operator to make calculations on input variables and gives the outcome stored in variable result.

3. Then, we use a set of print() statements to display the available operations (addition, subtraction, multiplication, and division).

4. Next, we use the input() function to prompt the user to select one of the operations by providing a number between 1 to 4, indicating the preferred operation.

5. Again, using the input() functions, we prompt the user to provide values for two variables, num1 and num2.

6. We then use the conditional if-elif statement to determine which operation must be executed depending on user input and provide the result thereof. Inside the statement-

• If the user selects option 1, then num1 and num2 are passed to the add() function, which adds the numbers and returns the outcome.
• For option 2, num1 and num2 are passed to the subtract() function. The function subtracts num2 from num1 and returns the outcome to the result variable.
• For option 3, num1 and num2 are passed to the multiply() function, which returns the product of the variable.
• For option 4, num1 and num2 are passed to the divide() function. The function first checks if the denominator is equal to 0. If true, it returns the string- Cannot divide by 0. If not, then it returns the outcome of the division.
• If none of the above options are picked, then the else block returns 'Invalid output'.

7. We then employ an if-else statetment to print the outcome. It first checks if the outcome is either 'Invalid Input' or 'Cannot be divided by zero' from option 4. If this is true, the same is printed to the console using print() method.

8. If it is false, then the else block is executed which prints the result along with the numerical value.

Creating GUI Calculator Program In Python Using Tkinter

Building a graphical user interface (GUI) application that allows users to do arithmetic operations through a visual interface is part of creating a GUI calculator using Tkinter in Python. Python's built-in GUI library, Tkinter, offers tools for creating windows, buttons, labels, and text fields. Here’s what a simple GUI calculator will look like:

Before diving into the code let’s take a look at the general approach that needs to be followed for coding this calculator:

• Import Tkinter: To create the GUI elements, import the Tkinter module.
• Build GUI Window: Construct the calculator application's main window.
• Facilitate user interaction: Add buttons, labels, and input fields to the user interface design to facilitate user interaction.
• Explain Functions: Make functions to carry out mathematical operations.
• Connect UI Functions: To execute an operation, connect the functions to the buttons.
• Launch the program: Initiate the main event loop in order to manage user input and display the GUI.

Now, let us try to understand this with an example code:

Output:

When this code is executed, a GUI window that looks like a basic calculator interface will appear. The calculator's buttons allow users to enter numbers, carry out arithmetic operations, clear their input, and obtain the result by clicking the "Equal" button.

Explanation:

The provided code snippet explains the steps involved in building a basic Tkinter calculator as well as its features and components.

1. We begin by importing the tinker module which helps create a window/ make graphical interfaces. This window will be our calculator with buttons, input boxes, and labels.
2. After that, the code uses a try-execpt block with if-elif conditional statement to define click_button() function and set up functions that will be called when any of the operation buttons ('+', '-', '*', '/') is clicked.
   • It attempts to extract numerical values from entry1 and entry2 fields, representing the user input.
   • Finally, it updates the label_result text to display the calculated result or an error message.
3. Now using, GUI Creation using Tkinter creates a Tkinter window (root) with the title "Simple Calculator". The idea is to create labels and widgets for user to input values.
   • Labels (label_num1, label_num2) to prompt users for input of the first and second numbers.
   • Creates entry widgets (entry1, entry2) where users can input numerical values.
4. Next, the code sets up buttons (button_add, button_subtract, button_multiply, button_divide) for addition, subtraction, multiplication, and division operations, respectively.
5. After that, it packs these widgets and buttons into the window, arranging them side by side using the pack() method with the side parameter.
6. Finally, an empty label_result label is used to display the result of the arithmetic operation performed.
7. The buttons have commands associated with them, calling click_button() with the respective operation when clicked. Users can input numbers into the entry1 and entry2 fields and choose an operation by clicking the buttons.

Conclusion

A calculator program in Python can be designed to perform mathematical operations like addition, subtraction, multiplication, and division efficiently, offering users a convenient tool for computational tasks. With its user-friendly interface and precise functionality, it simplifies complex calculations with just a few lines of code.

Creating a basic calculator with a graphical user interface (GUI) using the Tkinter library in Python offers an accessible way to perform simple arithmetic operations. The calculator lets users enter numbers, select arithmetic operations, and examine the answers instantaneously by utilizing Tkinter's features.

This calculator software illustrates the basic concepts of managing user input, carrying out mathematical operations, and presenting results in a graphical user interface. With the use of buttons that depict addition, subtraction, multiplication, and division operations, users may easily complete simple math calculations.

Additionally, the program uses error handling to handle situations like division by zero or invalid inputs, guaranteeing a seamless user experience by presenting the proper error messages as needed.

Overall, this straightforward calculator shows how to integrate user interaction, arithmetic operations, and error handling into a graphical environment using Tkinter. It is meant to serve as an introduction to the process of constructing a basic graphical application in Python.

Frequently Asked Questions

Q1. What are the calculation functions in Python?

The most popular Python calculation functions are as follows:

• add() is a function that combines two numbers.
• subtract(): Two numbers are subtracted using this function.
• multiply(): This function performs a multiplication of two numbers.
• divide(): This function splits a pair of numbers in half.
• pow(): A number is raised to a power using this function.
• sqrt(): This function yields a number's square root.
• abs(): This yields a number's absolute value.
• round(): This function rounds an integer to the number of decimal places that you specify.
• ceil(): Yields the smallest integer that is either greater than or equal to a given number.
• floor(): Yields the largest integer that is either equal to or less than a given number.

Q2. What are the basic math calculations in Python?

In Python programs, we can perform multiple mathematical operations and calculations on variables, expressions, etc.. We use elements called operators to perform these manipulations. Some of the most common/ basic mathematical calculations and their operators are-

• Addition: The addition operator (+) to add two numbers or variables and calculate the sum.
• Subtraction: The subtraction operator (-) is used to subtract one number/ variable from another.
• Multiplication: The multiplication operator (*) is used to multiply one variable/ number by another.
• Division: The division operator (/) is used to divide one variable/ number (the dividend) by another (the divisor).
• Floor division: When two numbers are divided by each other, the floor division operator (//) eliminates any fractional part and returns the whole number portion of the quotient or the division's outcome. For instance, 10 / 3 = 3. It divides integers and rounds to the next whole number every time.
• Modulus: The remainder of the division of one number by another is returned by the modulus operator (%). For example, 10% of 3 is equal to 1, since 10% of 3 is less than 1. It's frequently used to find out what's left over after division and whether a given number is divisible by another.
• Exponentiation: A number is raised to the power of another number using the exponentiation operator (**). For instance, since 2 raised to the power of 3 equals 8, 2 ** 3 equals 8. For the specified exponent, it denotes repeatedly multiplying the base number by itself.

These operators can be used to manipulate numbers in simple mathematical operations.

Q3. How do I make Python calculate faster?

There exist multiple methods for enhancing Python computation speed in order to maximize efficiency. Here are some pointers:

• Make use of effective algorithms and data Structures: Make use of data structures and algorithms that are appropriate for the given task. Generally, efficient algorithms work better for certain problems.
• Libraries such as NumPy provide optimized algorithms and data structures for numerical computations in mathematics.
• Make Use of Compiled Libraries: For data manipulation and numerical calculations, make use of compiled libraries like Pandas, sciPy, and numpy. Their use of low-level languages, such as Fortran and C/C++, speeds up computations.
• Reduce Looping and Vectorize Operations: Reduce the amount of time you spend looping over elements by using the vectorized operations that libraries like NumPy provide. Vectorized operations increase efficiency by executing calculations on whole arrays or matrices at once.
• Utilize iterators and generators: Iterators and generators can expedite operations and use less memory, particularly when working with large datasets. Rather than putting all of the data into memory, they enable the processing of the data in smaller portions.
• Optimization and Profiling: Locate performance bottlenecks in your code by using profiling tools such as line_profiler or cProfile. Refactor or rewrite the identified slow sections to make them more efficient.
• Cythonize Important Code Segments: Superset Cython translates Python code to C code, which is subsequently compiled into machine code. Important portions of the code can be substantially sped up in this way.

Q4. Is Calculate a function in Python?

In Python, calculate is not a built-in function like print(), len(), or input(). However, calculate can be a function if it is defined within the Python code. For instance, if you define a function named calculate in your Python code, it becomes a user-defined function that can perform a specific task or computation based on the code written within its block.

For example: Following code is defining a function named calculate that adds two numbers and returns the result:

def calculate(a, b):
    result = a + b
    return result

In this example, calculate is a function that takes two parameters (a and b), performs addition on them within the function block, and returns the result. You can call this function and pass different arguments to perform addition using the calculate function.

For example,

# Using the calculate function to add numbers
sum_result = calculate(5, 3)

print(sum_result) # Output will be 8

Here, the calculate function adds 5 and 3 together and returns the result, which is then printed to the console.

Q5. How do I start learning Python?

Learning Python is an excellent choice due to its simplicity and versatility. Here's a step-by-step guide on how to start learning Python:

• Establish Specific Goals: Recognize your motivation for learning Python. A goal will direct your learning path, whether it is for machine learning, web development, data analysis, etc.
• Install Python: Go to the official website, download, and install Python. Select the most recent stable version. Basic tools and an interpreter are included with Python.
• Select educational materials:

1. Online Education: Coursera, Udemy, and Unstop are online platforms that provide beginner-friendly structured courses.
2. Books: "Automate the Boring Stuff with Python" by Al Sweigart and "Python Crash Course" by Eric Matthes are two suggestions.
3. Tutorials and Documentation: Additional helpful resources include Python documentation, online tutorials from sites like W3Schools, and YouTube video tutorials.

• Recognize fundamental ideas:

1. Learn about the fundamental structure, indentation, and syntax of Python.
2. Know how to use variables and the many forms of data (integers, floats, strings, lists, tuples, and dictionaries).
3. Study functions, for-and while-loops, and if expressions.

• Always, always, always practice: Regular coding will help you to really comprehend things. You can use resources like LeetCode, HackerRank, or CodeSignal to solve coding puzzles on a daily basis.
• Implementing what you learned: What better way to test your concepts than by creating your own projects? Create little projects to put what you've learned to use. This will increase not only your in-depth knowledge of the language but also help you grasp the concept a little better.
• Investigate Specialized Areas: As you gain confidence with the fundamentals of Python, investigate particular areas based on your interests, such as web development (using Flask or Django), data analysis (using libraries like Pandas), machine learning (using TensorFlow or PyTorch).
• Involve the Community: To ask questions and pick up tips from others, join Python forums (such as r/learnpython on Reddit), communities (such as Stack Overflow), or go to Python meetups or events.
• Learn from Others: Assist other students, look for mentorship, or work in pairs with a more seasoned individual.
• Personal initiatives: Focus on your interest-based personal initiatives. Creating something useful will help you stay motivated and reinforce what you've learned.
• Keep Up to Date: Python is always changing. Stay current with libraries, best practices, and new features.

Q6. What is return in Python?

The return keyword in Python is used to deliver a value back to the caller within a function. Upon encountering a return statement in a called function, the interpreter promptly ends the function and returns any provided value to the caller.

Principal Aspects of Python's Return Type:

• Leaving a Position: No matter where in the function the return statement is located, it always results in the instant termination of the function's execution.
• Passing Values: The caller may optionally receive a value or the result of an expression via the return statement. As an illustration:

def add(a, b):
    return a + b

• Returning None: Python returns None implicitly if the return statement is missing or contains no value.
• Several Returns: Python functions are capable of having several return statements under certain circumstances. The function terminates, and the accompanying return statement is executed when a condition is satisfied.
• Returning Early: Functions can return a value and terminate early if a condition is met by using return in conditional statements. It facilitates the control of flow inside a function.

You may also like to read: 

1. Python Logical Operators, Short-Circuiting & More (With Examples)
2. Difference Between List And Tuple In Python With Examples
3. Difference Between Java And Python Decoded
4. Difference Between C and Python | C or Python - Which One Is Better?