Chapter 10: Problem 21

Describe the way that you use a temporary file in a program that modifies a record in a sequential access file.

Short Answer

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Question: Briefly describe how to modify a record in a sequential access file using a temporary file. Answer: To modify a record in a sequential access file using a temporary file, follow these steps: 1) Create a temporary file, 2) Read from the original file, 3) Modify the desired record, 4) Write the modified records to the temporary file, 5) Replace the original file with the temporary file, and 6) Close both the original and temporary files. This process ensures that the changes are properly saved and implemented.

Step by step solution

Understand the Problem

Before solving the problem, it is crucial to understand the difference between a sequential access file and a temporary file. A sequential access file is a file that can only be accessed and read in the order that the data was written. A temporary file, on the other hand, is a file used to store data temporarily during the execution of a program.

Create a Temporary File

To modify a record in a sequential access file, first create a temporary file. This can be done using a programming language of your choice. In this temporary file, we will store the updated records.

Read From the Original File

Open the original sequential access file, and begin reading through it. Read each record one by one in the order it was written.

Modify the Record

Once you locate the record that needs to be modified, make the necessary changes. It is important to ensure that the changes are valid and that they adhere to any constraints or rules established by the program.

Write the Modified Records to the Temporary File

After modifying the record, write it to the temporary file. As you continue to read through the original file, write all other records that do not require any modifications to the temporary file as well.

Replace the Original File with the Temporary File

Once you have finished reading through the entire original file and have written all modified and unmodified records to the temporary file, replace the original file with the temporary file. This can be done by renaming the temporary file to match the name of the original file or by deleting the original file and then renaming the temporary file.

Clean Up

Finally, remember to close both the original sequential access file and the temporary file. This will ensure that the changes are saved and that no additional modifications can be made inadvertently. After following these steps, you will have successfully modified a record in a sequential access file using a temporary file.

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Describe the way that you use a temporary file in a program that modifies a record in a sequential access file.

Short Answer

Step by step solution

Understand the Problem

Create a Temporary File

Read From the Original File

Modify the Record

Write the Modified Records to the Temporary File

Replace the Original File with the Temporary File

Clean Up

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