Topic 6.5: File processing Questions

A text file, members, stores three lines for each member of a club: surname, then town, then membership number. An algorithm must read members line by line and write only the surnames into a new text file, surnames. Both files are currently closed. Describe the steps this algorithm would follow.

Explain why a file should be closed after use.

State two modes in which a file can be opened.

A text file, contacts, holds four lines per person: name, phone, email and town. An algorithm writes only the email addresses into a new text file, emails. Both files are closed. Describe the steps the algorithm follows.

A text file, results, stores each pupil on two lines: name, then score. An algorithm copies only the names of pupils who scored over 50 into a new file, passed. Both files are closed. Describe the steps the algorithm follows.

Explain two advantages of storing data in a binary file rather than a text one.

Determine the size of a file holding 5000 records of 120 bytes each, in megabytes. Take 1 MB as 1 000 000 bytes.

State the three basic operations performed on a file.

Distinguish between a text file and a binary file.

Distinguish between reading a file sequentially and accessing it directly.

Explain why direct access requires fixed-length records.

Determine the byte position of record 250 in a file of fixed-length 80-byte records, counting the first record as record 0.

Determine which record number begins at byte 48 000 in that same file.

Explain why a program should not assume a file it reads is correctly formatted.

Choose what opening a file in write mode does to existing contents.

Choose what direct access to a record requires.

Suggest why a log file should be opened in append mode rather than write mode.

Suggest why a comma-separated format causes problems for data containing commas.

Explain two advantages of storing data in a text file rather than a binary one.

Write a Java program that appends a new record to the end of a text file called records.txt without losing what is already there.