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

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**Answer:** You can check if a file exists using the `os.path.exists` function, and if it doesn't exist, you can create it using the `open` function in 'write' mode. Here's a simple code snippet: ```python import os file_exists = os.path.exists("data.txt") if not file_exists: with open("data.txt", "w"): pass ```

Step by step solution

Import necessary modules

First, import the `os` module, which will allow us to check if the file "data.txt" exists or not. ```python import os ```

Check if the file exists

Use the `os.path.exists` function to check if the file "data.txt" exists or not. Store the result in a variable called `file_exists`. ```python file_exists = os.path.exists("data.txt") ```

Create the file if it doesn't exist

If `file_exists` is False, it means the file doesn't exist, so we'll create it using the `open` function with the 'w' (write) mode and then immediately close the file. ```python if not file_exists: with open("data.txt", "w"): pass ```

Open the file for input and output

Now that we have ensured the file exists, we can open it for both input (read) and output (write) using the 'r+' mode in the `open` function. ```python with open("data.txt", "r+") as file: # Perform input and output operations pass ``` With these steps, we have written a code that checks for the existence of the file "data.txt", creates it if it doesn't exist, and then opens it for both input and output operations.

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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 modules

Check if the file exists

Create the file if it doesn't exist

Open the file for input and output

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