Chapter 6: File Handling and Exceptions

6.1 Introduction to File Handling 6.1.1 Opening and closing files Explanation: File handling allows you to work with external files. You can open a file using the open() function, perform operations on it, and close it using the close() method. Example:

python

///Example

file = open("example.txt", "r")  # Opening a file in read mode

content = file.read()  # Reading the file content

print(content)

file.close()  # Closing the file

 

6.1.2 File modes: read, write, append Explanation: Files can be opened in different modes. "r" mode is for reading, "w" mode is for writing (overwriting existing content), and "a" mode is for appending (adding to existing content). Example:

python

///Example

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

file.write("Hello, World!")  # Writing content to the file

file.close()

 

6.1.3 File paths and directories Explanation: File paths specify the location of a file on the system. You can work with files in different directories by providing the appropriate file path. Example:

python

///Example

file = open("path/to/file.txt", "r")  # Opening a file with a specific path

content = file.read()

print(content)

file.close()

 

6.2 Exception Handling 6.2.1 Handling exceptions with try-except Explanation: Exception handling allows you to catch and handle errors that occur during program execution. The try-except block is used to catch and handle specific exceptions. Example:

python

///Example

try:

    num = int(input("Enter a number: "))

    result = 10 / num

    print("Result:", result)

except ValueError:

    print("Error: Invalid input. Please enter a valid number.")

except ZeroDivisionError:

    print("Error: Cannot divide by zero.")

 

6.2.2 Handling multiple exceptions and the else clause Explanation: You can handle multiple exceptions by using multiple except blocks. The else clause is executed if no exception occurs. Example:

python

///Example

try:

    num = int(input("Enter a number: "))

    result = 10 / num

except ValueError:

    print("Error: Invalid input. Please enter a valid number.")

except ZeroDivisionError:

    print("Error: Cannot divide by zero.")

else:

    print("Result:", result)

 

6.2.3 The finally clause and resource cleanup Explanation: The finally clause is used to define code that must be executed regardless of whether an exception occurs. It is commonly used for resource cleanup. Example:

python

///Example

try:

    file = open("example.txt", "r")

    content = file.read()

    print(content)

except FileNotFoundError:

    print("Error: File not found.")

finally:

    file.close()  # File is closed even if an exception occurs

 

This chapter covers file handling and exception handling in Python. File handling allows you to read from and write to external files, while exception handling enables graceful error handling. The examples provided demonstrate the usage and syntax of each topic, helping readers understand how to apply these concepts in their own programs.