Python - Reading and Writing Files

In Python, you can use the read() method to read the contents of a file. The read() method reads the entire content of the file as a single string. Here's an example program demonstrating how to use the read() method:

# Open the file in read mode
with open('example.txt', 'r') as file:
    # Use the read() method to read the entire content of the file
    content = file.read()
    print("File Content:", content)

In this example, the file 'example.txt' is opened in read mode using the with statement. The read() method is then called on the file object to read the entire content of the file into the variable content.

The output of the program will be:

File Content: This is the content of the example file.

In file handling, a file pointer is a marker or an indicator that points to the current position in a file. It keeps track of the location where the next read or write operation will occur. The file pointer is crucial for sequential access to the contents of a file.

When a file is opened, the file pointer is initially positioned at the beginning of the file (position 0). As data is read or written, the file pointer moves to the next position. The concept of the file pointer is essential for navigating through the content of a file during file operations.

Here is an example program that demonstrates the concept of a file pointer in file handling:

# Open the file in read mode
with open('example.txt', 'r') as file:
    # Read the first 20 characters using read()
    content_part1 = file.read(20)
    print("Content Part 1:", content_part1)

    # Check the current position of the file pointer
    current_position = file.tell()
    print("Current File Pointer Position:", current_position)

    # Move the file pointer to a specific position (e.g., position 10)
    file.seek(10)

    # Read the next 10 characters from the new position
    content_part2 = file.read(10)
    print("Content Part 2:", content_part2)

In this example, the file 'example.txt' is opened in read mode using the with statement. The read() method is used to read the first 20 characters of the file, and the tell() method is used to get the current position of the file pointer. The seek() method is then used to move the file pointer to position 10, and another read() operation is performed to read the next 10 characters from the new position.

The output of the program will be:

Content Part 1: This is the content 
Current File Pointer Position: 20
Content Part 2: the cont

To read a specific number of characters from a file in Python, you can use the read() method and specify the number of characters you want to read. Here's an example program that demonstrates how to read a specific number of characters from a file:

# Open the file in read mode
with open('example.txt', 'r') as file:
    # Read the first 15 characters from the file
    content_part = file.read(15)
    print("Read Content:", content_part)

In this example, the file 'example.txt' is opened in read mode using the with statement. The read() method is then used to read the first 15 characters from the file, and the result is stored in the variable content_part.

The output of the program will be:

Read Content: This is the con

The readline() method in Python is used for reading a single line from a file. It reads characters from the current position of the file pointer until it encounters a newline character (\n) or reaches the end of the file. The readline() method is useful when you want to process a file line by line.

Here's an example program that demonstrates the purpose of the readline() method:

# Open the file in read mode
with open('example.txt', 'r') as file:
    # Read the first line from the file
    line1 = file.readline()
    print("Line 1:", line1)

    # Read the next line from the file
    line2 = file.readline()
    print("Line 2:", line2)

In this example, the file 'example.txt' is opened in read mode using the with statement. The readline() method is then used to read the first line from the file and store it in the variable line1. Subsequently, another readline() operation is performed to read the next line and store it in line2.

The output of the program will be:

Line 1: This is the first line.
Line 2: This is the second line.