Chapter 12: Problem 46

Write code that opens the file data.txt for both input and output, but first determines if the file exists. If the file does not exist, the code should create it, then open it for both input and output.

Short Answer

Expert verified

Answer: We can create the required Python script using the following steps: 1. Import the `os` module. 2. Use the `os.path.exists()` function to check if "data.txt" exists. 3. If it doesn't exist, use the `open()` function with the `'w'` mode to create it. 4. Finally, open the file for input and output using the `open()` function with the `'r+'` mode. Here's the complete code: ```python import os file_exists = os.path.exists('data.txt') if not file_exists: with open('data.txt', 'w') as f: pass with open('data.txt', 'r+') as f: # Perform input and output operations as needed pass ```

Step by step solution

Import necessary module

First, we need to import the `os` module, which provides us with many useful functionalities, such as checking for a file's existence and creating new files. ```python import os ```

Check if the file exists

We will use the `os.path.exists()` function to check if the file exists or not. The `exists()` function returns `True` if the file is present, and `False` otherwise. ```python file_exists = os.path.exists('data.txt') ```

Create the file if it does not exist

If the `file_exists` variable is `False` (i.e., the file does not exist), we will create the file using the `open()` function with the `'w'` mode, which creates a file if it is not already present. After creating the file, we need to close it as well. ```python if not file_exists: with open('data.txt', 'w') as f: pass ```

Open the file for input and output

Finally, we will open the file for input and output purposes using the `open()` function with the `'r+'` mode, which allows both reading and writing to the file. Also, we need to close the file after completing the required operations. ```python with open('data.txt', 'r+') as f: # Perform input and output operations as needed pass ``` The complete code should look like this: ```python import os file_exists = os.path.exists('data.txt') if not file_exists: with open('data.txt', 'w') as f: pass with open('data.txt', 'r+') as f: # Perform input and output operations as needed pass ```

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Write code that opens the file data.txt for both input and output, but first determines if the file exists. If the file does not exist, the code should create it, then open it for both input and output.

Short Answer

Step by step solution

Import necessary module

Check if the file exists

Create the file if it does not exist

Open the file for input and output

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