Python open() Function

open() function is used to open a file in Python. It allows you to read data from a file, write new data, append content or create a new file depending on the mode specified. It returns a file object that can be used to perform file operations.

Example: The following example opens a file in read mode and displays its contents.

f = open("data.txt", "r")
print(f.read())
f.close()

Output

Hello World

Explanation: open("data.txt", "r") opens the file in read mode and f.read() returns the entire contents of the file.

Syntax

open(file, mode="r")

Parameters:

• file: Name or path of the file to open.
• mode: Specifies how the file should be opened.

Return Value: Returns a file object that can be used to read, write or modify the file.

Common File Modes

Examples

Example 1: The following example creates a new file using x mode. A new file is created only if a file with the same name does not already exist.

f = open("notes.txt", "x")
f.close()
print("File created")

Output

File created

Explanation: open("notes.txt", "x") creates a new file. If notes.txt already exists, Python raises a FileExistsError.

Example 2: The following example writes text to a file and then reads the same file to verify the contents.

f = open("message.txt", "w")
f.write("Python File Handling")
f.close()

f = open("message.txt", "r")
print(f.read())
f.close()

Output

Python File Handling

Explanation: open("message.txt", "w") opens the file in write mode and f.write() stores the text in the file. The file is then reopened using "r" mode to read its contents.

Example 3: The following example appends new content to an existing file without removing the previous data.

f = open("log.txt", "a")
f.write("\nNew entry added")
f.close()

f = open("log.txt", "r")
print(f.read())
f.close()

Output

Application Started
New entry added

Explanation: open("log.txt", "a") opens the file in append mode, so f.write() adds the new text at the end of the existing content instead of replacing it.