Introduction to File handling in Python

Python From Beginner to Advanced

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File handling is a critical aspect of any programming language, including Python. It allows programs to interact with files on the operating system, enabling the reading and writing of data, among other operations. Understanding how to handle files is essential for applications that require data persistence, such as logging activities, processing user inputs, or managing output data.

Purpose and Benefits of File Handling

File handling is necessary for:

Data Storage: Store data permanently in files that can outlast the program's runtime.
Data Retrieval: Retrieve and use data stored previously, enabling data analysis and reporting.
Content Manipulation: Modify files directly through a program to update logs, configurations, and other information dynamically.
Resource Management: Efficiently manage resources by only loading data into memory when needed, which is crucial for handling large datasets.

File handling provides a robust way to perform these tasks efficiently and effectively, making it an indispensable skill for developers.

Opening a File in Python

To work with files in Python, you begin by opening a file. The open() function is used to open a file and returns a file object that can be used to read, write, or append data.

Example: Opening a File

Python3

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Explanation:

file = open('example.txt', 'r'): This line opens a text file named 'example.txt' in read mode ('r'). It assigns a file object to the variable file.
print(file.read()): This line reads the entire contents of the file using the read() method of the file object and then prints it to the console.
file.close(): This line closes the file object. It's important to close the file when you're done with it to free up system resources and ensure that any changes are saved properly.

Output:

Prints the file content.

File Opening Modes

Here is a table detailing various file opening modes available in Python, which define how the file will be handled once opened:

Sr.No.	Mode	Description
1	`r`	Opens a file for reading only. The file pointer starts at the beginning.
2	`rb`	Opens a file for reading only in binary format. The file pointer starts at the beginning.
3	`r+`	Opens a file for both reading and writing. The file pointer starts at the beginning.
4	`rb+`	Opens a file for both reading and writing in binary format. The file pointer starts at the beginning.
5	`w`	Opens a file for writing only. Overwrites the file if it exists or creates a new one if it does not.
6	`wb`	Opens a file for writing only in binary format. Overwrites the file if it exists or creates a new one if it does not.
7	`w+`	Opens a file for both writing and reading. Overwrites the existing file if it exists or creates a new one if it does not.
8	`wb+`	Opens a file for both writing and reading in binary format. Overwrites the existing file if it exists or creates a new one if it does not.
9	`a`	Opens a file for appending; the file pointer is at the end of the file if the file exists. Creates a new file for writing if it does not.
10	`ab`	Opens a file for appending in binary format; the file pointer is at the end of the file if the file exists. Creates a new one if it does not.
11	`a+`	Opens a file for both appending and reading; the file pointer is at the end of the file if it exists. Creates a new one if it does not.
12	`ab+`	Opens a file for both appending and reading in binary format; the file pointer is at the end of the file if it exists. Creates a new one if it does not.
13	`x`	Opens a file exclusively for creation, failing if the file already exists.

This comprehensive overview provides the necessary foundation to manipulate files in Python, ensuring data is handled correctly according to the application's needs.

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