Opening a File:
Before you can perform any operations on a file, you need to open it. Python provides the open() function for this purpose. Here’s a basic example of how to open a file:

file = open("example.txt", "r") # Open "example.txt" in read-only mode

In the code above:

“example.txt” is the name of the file you want to open.
“r” specifies the mode in which the file is opened. In this case, “r” stands for read-only mode.
Common file modes include:

“r”: Read-only mode (default).
“w”: Write mode (creates a new file or overwrites an existing file).
“a”: Append mode (appends data to an existing file).
“b”: Binary mode (for binary files, e.g., “rb” for reading a binary file).

Reading from a File:
Once you’ve opened a file for reading, you can read its contents using various methods. One common method is read():

file = open("example.txt", "r")
content = file.read()
print(content)
file.close()

In this code snippet, read() reads the entire content of the file and stores it in the content variable. Don’t forget to close the file using close() when you’re done to free up system resources.

You can also read a file line by line using a for loop:

file = open("example.txt", "r")
for line in file:
print(line)
file.close()

This code snippet reads the file line by line, which is useful for large files that might not fit into memory all at once.

Writing to a File:
To write data to a file, you can open it in write mode (“w”) or append mode (“a”) using the open() function. Here’s an example of writing data to a file:

file = open("output.txt", "w")
file.write("Hello, World!\n")
file.write("This is a test file.")
file.close()

In this example, we create a new file called output.txt and write two lines of text to it. If the file already exists, using “w” mode will overwrite its contents, so be cautious.