Skip to main content

Working with Files and Input/Output

In this section, we'll explore how to read and write files in Python and handle input/output operations. These skills are crucial for interacting with external data sources and building more advanced programs.

Reading and Writing Text Files​

Python provides built-in functions for reading and writing text files. Let's start with reading a file:

# Reading a file
file_path = "example.txt"

# Method 1: Using the `open()` function and `read()` method
file = open(file_path, "r")
content = file.read()
file.close()
print(content)

# Method 2: Using the `with` statement (recommended)
with open(file_path, "r") as file:
    content = file.read()
    print(content)

In the above code, we first define the path to the file we want to read. Then, we have two methods for reading the file:

  • Method 1 uses the open() function to open the file, followed by the read() method to read its contents. Finally, we close the file using the close() method.

  • Method 2 is more recommended and uses the with statement. It automatically handles file closing, even if an exception occurs.

Now, let's see how to write to a file:

# Writing to a file
file_path = "output.txt"

# Method 1: Using the `open()` function and `write()` method
file = open(file_path, "w")
file.write("Hello, Python!")
file.close()

# Method 2: Using the `with` statement (recommended)
with open(file_path, "w") as file:
    file.write("Hello, Python!")

Similar to reading, we define the file path and use two methods for writing:

  • Method 1 uses the open() function with the file mode set to "w" (write), followed by the write() method to write the desired content. Finally, we close the file.

  • Method 2 is the recommended approach using the with statement. We open the file in write mode ("w"), use the write() method to write the content, and the file is automatically closed when the with block is exited.

Handling Exceptions and Error Messages​

When working with files or performing input/output operations, errors can occur. Python provides mechanisms to handle exceptions gracefully. Let's take a look at an example:

# Exception handling
file_path = "example.txt"

try:
    with open(file_path, "r") as file:
        content = file.read()
        print(content)
except FileNotFoundError:
    print("File not found!")
except IOError:
    print("An error occurred while reading the file!")
except Exception as e:
    print(f"An error occurred: {str(e)}")

In the above code, we use a try-except block to catch and handle exceptions. If the file specified by file_path does not exist, a FileNotFoundError will be raised. If an error occurs while reading the file, an IOError will be raised. The Exception class is a base class for all exceptions, and it will catch any other unexpected errors.

Working with Standard Input and Output​

Python allows you to interact with standard input (stdin) and standard output (stdout). This is useful for reading user input and displaying output. Here's an example:

# Standard input and output
name = input("Enter your name: ")
age = input("Enter your age: ")

print(f"Hello, {name}! You are {age} years old.")

In the above code, we use the input() function to prompt the user for input. The user's name and age are stored in variables. Then, we use the print() function to display a message that includes the provided name and age.

These are the basics of working with files, input/output operations. In the next section, we'll dive into object-oriented programming (OOP) concepts.

Github Repo​

info

You can refer to and clone the code samples for this tutorial from the GitHub repository.

To clone the repository, you can use the following command:

git clone https://github.com/certifysphere/python-code-samples.git

You can then navigate to the /src directory to access all the code samples given in this tutorial.