Working with files in Python

Learn Python variables with this beginner-friendly guide. Understand variable naming rules, assignments, and operations with examples and exercises. Perfect for students and professionals starting their Python journey.

1. Reading and Writing Files

• Python provides simple methods to read from and write to files using the built-in open() function.
• You can open files in different modes like read (r), write (w), and append (a).

#### Reading a File:

• Use open() with mode 'r' to read from a file.
• Use .read() to read the entire file or .readlines() to read the file line by line.

Example of reading a file:

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

#### Writing to a File:

• Use open() with mode 'w' to write to a file. This will overwrite the file if it exists.
• Use 'a' to append content to an existing file.

Example of writing to a file:

   with open('example.txt', 'w') as file:
       file.write("Hello, this is a test file.\n")
       file.write("Python makes file handling easy.")

### 2. Handling File Exceptions

• You should always handle potential errors when working with files, such as file not found or permission issues.
• You can use a try and except block to handle these exceptions.

Example:

   try:
       with open('nonexistent_file.txt', 'r') as file:
           content = file.read()
   except FileNotFoundError:
       print("The file was not found.")

3. Reading User Input

• You can use the input() function to capture user input.
• By default, input() returns a string, so you may need to convert it to another data type (e.g., int() or float()).

Example:

   name = input("Enter your name: ")
   age = int(input("Enter your age: "))
   print(f"Hello {name}, you are {age} years old.")

4. Writing User Input to a File

• Combine reading user input with file writing. Ask the user for input and save their response to a file.

Example:

   user_input = input("Enter some text to save to the file: ")
   with open('user_input.txt', 'w') as file:
       file.write(user_input)