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Python File

File Input/Output mechanisms in Python.

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* File I/O in Python is a fundamental concept that enables you to work with external files efficiently.

File I/O

File I/O (Input/Output) in Python refers to the process of reading from and writing to files on the disk. It allows you to interact with external files, which is essential for tasks like reading configuration files, processing data stored in files, and storing output data.

• Explanation of Python file I/O:

Opening a File:

To open a file in Python, you use the 'open()' function. It takes two arguments: the file name (or path) and the mode in which you want to open the file.

File Modes
'r': Read mode. Opens the file for reading. (default mode)
'w': Write mode. Opens the file for writing. Creates a new file or truncates the existing file to zero length.
'a': Append mode. Opens the file for writing. Creates a new file if it does not exist or appends to the end of the existing file.
'b': Binary mode. Opens the file in binary mode.
't': Text mode. Opens the file in text mode. (default mode)
py Copy Code 
# Opening a file in read mode
file = open('example.txt', 'r')

# Opening a file in write mode
file = open('example.txt', 'w')

# Opening a file in binary mode for writing
file = open('example.txt', 'wb')

# Opening a file in text mode for reading
file = open('example.txt', 'rt')

Reading from a File:

You can read from a file using various methods provided by file objects:

⤏ read(size): Reads and returns at most 'size' bytes from the file.

⤏ readline(): Reads a single line from the file.

⤏ readlines(): Reads all lines from the file and returns as a list.

example.txt
txt (Text File) Copy Code 
The file opened & read successfully.
main.py
py Copy Code 
file = open('example.txt', 'r')
content = file.read()  # Reads the entire file
line = file.readline()  # Reads a single line
lines = file.readlines()  # Reads all lines into a list
file.close()  # Always close the file after you're done with it
                                print(content)  # Print all lines
Output: 
The file opened & read successfully.

Writing to a File:

You can write to a file using the 'write()' method:

py Copy Code 
file = open("example.txt", "w")
file.write("File I/O concepts in Python.\n")
file.close()

Appending to a File:

You can append to an existing file using the 'a' mode or 'write()' method:

py Copy Code 
file = open('example.txt', 'a')
file.write("Appending text to the file.\n")
file.close()

Note: Always close the file after you're done with it to release system resources: 'file.close()'

with Statement:

Python provides a cleaner way to work with files using the with statement. It automatically closes the file when you're done with it:

py Copy Code 
with open("example.txt", "r") as file:
⠀content = file.read()
print(content)  # Print all the lines
# File is automatically closed after exiting the `with` block
Output: 
File I/O concepts in Python.
Appending text to the file.

Remember: handle exceptions and close files properly to avoid resource leaks and potential errors.

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