Working with Files in Python

Working with files in Python is straightforward and can be done using built-in functions. Here’s a quick overview of the basic operations:

1. Opening a File

You can open a file using the open() function. The syntax is:

file = open("filename.txt", "mode")

• "mode" specifies the mode in which the file is opened. Common modes are:

  • "r": Read (default mode)

  • "w": Write (creates a new file or truncates an existing one)

  • "a": Append (writes to the end of the file)

  • "b": Binary mode (e.g., "rb" or "wb" for reading or writing binary files)

  • "+": Updating (reading and writing)

Example:

file = open("example.txt", "r")

"+" mode will overwrite the content in the file.

2. Reading from a File

You can read the contents of a file using various methods:

• read(): Reads the entire file.

• readline(): Reads one line at a time.

• readlines(): Reads all lines and returns them as a list.

Example:

content = file.read()           # Reads the whole file
first_line = file.readline()    # Reads the first line
all_lines = file.readlines()    # Reads all lines into a list

Alternatively:

for line in file:
    print(line)

3. Writing to a File

You can write to a file using the write() or writelines() methods.

• write(): Writes a string to the file.

• writelines(): Writes a list of strings to the file.

Example:

file = open("example.txt", "w")
file.write("Hello, World!\n")
file.writelines(["Line 1\n", "Line 2\n"])

4. Closing a File

It’s important to close the file after you’re done with it to free up resources.

file.close()

Alternatively, you can use a with statement to automatically close the file:

with open("example.txt", "r") as file:
    content = file.read()

5. Working with Binary Files

For binary files, use "rb" or "wb" mode.

Example:

with open("image.jpg", "rb") as file:
    data = file.read()

6. Checking if a File Exists

You can check if a file exists using the os.path module:

import os

if os.path.exists("example.txt"):
    print("File exists")

7. Deleting a File

To delete a file, you can use os.remove():

os.remove("example.txt")

8. Working with Paths

The os and pathlib modules help with file path operations:

• os.path: For basic path manipulations.

• pathlib.Path: For a more modern and flexible approach.

Example using pathlib:

from pathlib import Path

path = Path("example.txt")
if path.exists():
    print(f"{path.name} exists")

These basics should cover most of your file operations in Python.