File Handling

File IO Modes

Python’s built-in open() function allows for various file access modes, influencing how the file is handled during operations. These modes are specified as a second argument to open().

Common Modes:

• 'r' (read): Opens the file for reading. This is the default mode. An error occurs if the file does not exist.
• 'w' (write): Opens the file for writing. If the file exists, its contents are overwritten. If the file does not exist, a new file is created.
• 'x' (exclusive creation): Opens the file for writing, but only if the file does not already exist. If the file exists, an error is raised.
• 'a' (append): Opens the file for writing. If the file exists, new data is appended to the end of the file. If the file does not exist, a new file is created.
• 'b' (binary): Used in conjunction with other modes ('rb', 'wb', 'ab', 'xb'). Opens the file in binary mode. Crucial for working with non-text files (images, executables, etc.). Data is read and written as bytes.
• 't' (text): Used in conjunction with other modes ('rt', 'wt', 'at'). Opens the file in text mode (this is the default). Data is read and written as strings. Handles newline characters according to the system’s convention.
• '+' (update): Used with other modes ('r+', 'w+', 'a+', 'x+'). Opens the file for both reading and writing.

Example Usage:

# Reading a file
f = open("my_file.txt", "r")
contents = f.read()
f.close()

# Writing to a file
f = open("my_file.txt", "w")
f.write("Hello, world!")
f.close()

# Appending to a file
f = open("my_file.txt", "a")
f.write("\nThis is appended text.")
f.close()

#Binary read
f = open("image.jpg","rb")
image_data = f.read()
f.close()

# safer way to handle files: using 'with' statement. Auto closes file for you.
with open("my_file.txt", "r") as file:
    contents = file.read()
    print(contents)

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