PROJECT 14 - LIBRARY SYSTEM

Lab 1 Overview

Learn to perform basic file input/output (I/O) operations in Python, focusing on creating, writing, and reading text files. This lab will introduce you to managing data with files, a fundamental skill in programming.

Introduction to File Handling in Python

Files are a way to store data on your disk, and Python provides built-in functions that make working with files straightforward. When you're programming, you'll often need to read data from files or write data to files, and Python's file handling capabilities are designed to handle these tasks efficiently.

Opening a File

To work with a file, you first need to open it using the open function.
You can open a file in several modes:

• 'r' for reading (default)

• 'w' for writing (creates a new file or truncates existing)

• 'a' for appending

• 'r+' for both reading and writing

Here's how you can open a file:

with open('example.txt', 'w') as file:

    # The file is now open for writing

Writing to a File

Once a file is opened in write mode, you can write text to it using the write() method:

with open('example.txt', 'w') as file:

    file.write('Hello, world!')

Reading from a File

To read the contents of a file, you need to open it in read mode.

with open('example.txt', 'r') as file:

    content = file.read()  # Reads the entire file contents

    print(content)

Error Handling

Handling potential errors during file operations is crucial. Errors can occur for various reasons such as attempting to read a file that doesn't exist or encountering access permission issues. Python provides several built-in exceptions for handling file-related errors. The most common is FileNotFoundError, which occurs when a file that is attempted to be read doesn't exist.

try:

    with open('example.txt', 'r') as file:

        print(file.read())

except FileNotFoundError:

    print("The file does not exist.")

File Iteration

Python’s file objects can be iterated over line by line using a simple for loop, which can be particularly useful for large files or when you need to process each line individually. This example reads one line at a time, prints it, and then moves on to the next.

with open('example.txt', 'r') as file:

    for line in file:

        print(line.strip())  # strip() removes the newline character at the end of each line