How to Read from a File Opened in Python's 'w ' Mode?

Understanding Python File Mode "w "

The "w " mode in Python open a file for both writing and updating. It overwrites the existing file, and if the file doesn't exists, it creates a new one.

Unlike modes such as "r" (read only) and "w" (write only), "w " allows you to both write and read data from the file. However, a common question arises when using the "w " mode: how do you read from a file that you've opened with "w "?

To read from a file opened with "w ", you need to perform the following steps:

1. Open the file in "w " mode: This is done using the open() function, as shown below:

file = open("myfile.txt", "w+")

2. Write data to the file: Use the write() function to write data to the file:

file.write("Hello, world!")

3. Seek the beginning of the file: Once you've finished writing, use the seek() function to move the file pointer to the beginning of the file:

file.seek(0)

4. Read data from the file: Now you can use the read() function to read data from the file:

data = file.read()

Here's a complete example of opening a file in "w " mode, writing some data, and then reading it:

with open("myfile.txt", "w+") as file:
    # Write data to the file
    file.write("This is line 1.\n")
    file.write("This is line 2.\n")
    
    # Seek the beginning of the file
    file.seek(0)
    
    # Read data from the file
    data = file.read()
    
    # Print the data
    print(data)

Output:

This is line 1.
This is line 2.

The above is the detailed content of How to Read from a File Opened in Python's 'w ' Mode?. For more information, please follow other related articles on the PHP Chinese website!