Chapter 12: Problem 48

The inforile file stream object is used to sequentially access data. The program has already read to the end of the file. Write code that rewinds the file.

Short Answer

Expert verified

Answer: To rewind a file using the 'inforile' file stream object in Python, you can use the seek() function with an offset of 0 to reset the file pointer to the beginning of the file. Here is an example: ```python # Open the file in read mode inforile = open("example.txt", "r") # Read the file contents file_contents = inforile.read() # Rewind the file pointer to the beginning inforile.seek(0) # Close the file inforile.close() ``` This will reset the file pointer to the beginning so that it can be read again sequentially from the first character.

Step by step solution

Open the file using 'inforile' file stream object

First, open the file with the 'inforile' file stream object. It will look something like this: ```python inforile = open("example.txt", "r") ``` Make sure that the file is opened in read mode (which is represented by "r"), as we will only be reading the contents of the file.

Read the file to the end

As the exercise states, we assume that the program has already read the contents of the file to the end. An example of how this can be done is shown below: ```python file_contents = inforile.read() ```

Rewind the file pointer

To rewind the file, or to reset the file pointer to the beginning of the file, we will use the seek() function. The function takes an argument 'offset' which represents the position at which we want to set the file pointer. Since we want to move the file pointer to the beginning, we will use an offset of 0. Call the seek() function as shown below: ```python inforile.seek(0) ```

Verify that the file pointer is at the beginning

To verify that the file pointer is back at the beginning of the file, we can try reading the contents of the file again and see if it contains the same content as before. We can do this using the read() function: ```python rewound_file_contents = inforile.read() ``` Now you can compare 'file_contents' and 'rewound_file_contents' to check if they are the same, which would mean that the file pointer has been successfully rewound to the beginning.

Close the file

Finally, remember to close the file after you are done using it. This is an important step for maintaining good file I/O habits. ```python inforile.close() ```

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The inforile file stream object is used to sequentially access data. The program has already read to the end of the file. Write code that rewinds the file.

Short Answer

Step by step solution

Open the file using 'inforile' file stream object

Read the file to the end

Rewind the file pointer

Verify that the file pointer is at the beginning

Close the file

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