Question

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

Short answer

Question: Explain the process of using a temporary file to modify a record in a sequential access file. Answer: The process involves the following steps: 1. Open the source and temporary files. 2. Read records from the source file until the desired record is found. 3. Compare the read record with the target record and write any non-target records to the temporary file. 4. Modify the desired record. 5. Write the modified record to the temporary file. 6. Continue reading and writing records until the end of the source file. 7. Close both the source and temporary files. 8. Rename the temporary file to replace the original file and delete the original file if necessary. 9. Reopen the modified file to access the updated records.

Step-by-step solution

Open the source and temporary files

First, open the source (original) file that contains the record to be modified, as well as a temporary file where the modified records will be stored temporarily.

Read the records from the source file

Read the records from the source file one by one until the desired record to be modified is found or until the end of the file is reached.

Check for the record to be modified

Compare the read record with the record to be modified. If it is not the target record, write the record in the temporary file. If it is the target record, proceed to step 4.

Modify the record

When the target record is found, make the necessary modifications to the record.

Write the modified record to the temporary file

Write the modified record into the temporary file.

Continue reading and writing records

Continue to read records from the source file and write them to the temporary file until the end of the source file is reached.

Close both files

Close both the source and temporary files.

Rename and delete files

Rename the temporary file to have the same name as the original file, effectively replacing the original source file. Delete the original source file if necessary.

Reopen the modified file

Finally, reopen the modified file to access the updated records. The original record has now been modified and stored in a sequential access file using a temporary file.