Write pseudocode to handle text files that consist of one or more lines

What is a file?

A file is a collection of data stored on a computer. Think of it as a 📚 book where each line is a page. In A‑Level CS you’ll often work with text files, which are just sequences of characters separated by line breaks.

Before you can read or write, you must open the file. In pseudocode:

OPEN fileName FOR mode
  // mode = READ or WRITE
  IF file NOT found THEN
    PRINT "Error: file does not exist"
  END IF
  

Analogy: Opening a file is like opening a diary. You choose whether to read or write in it.

Use a loop to process each line until the end of file (EOF) is reached.

SET lineNumber = 1
WHILE NOT EOF(file) DO
  READ line FROM file
  PRINT "Line " + lineNumber + ": " + line
  INCREMENT lineNumber
END WHILE
  

Here, EOF(file) is a condition that becomes true when there are no more lines to read.

When writing, you usually append to the end of the file or overwrite it entirely.

OPEN fileName FOR WRITE
FOR EACH item IN dataList DO
  WRITE item TO file
END FOR
CLOSE file
  

Analogy: Writing is like adding new chapters to a book. Each WRITE adds a new page.

Always close the file to free resources and ensure data is saved.

CLOSE file
  

Think of it as closing the diary after you’re done writing.

?? Show the full pseudocode for opening, reading, writing, and closing.

?? Explain the purpose of each step (e.g., why we check for EOF).

?? Use clear variable names like file, line, lineNumber.

?? Include error handling (e.g., file not found).

?? Remember to close the file – a common exam mistake.

Think of a file as a diary 📓:

1. Open the diary (OPEN).
2. Read each page until the end (WHILE NOT EOF).
3. Add new pages (WRITE).
4. Close the diary (CLOSE).

Keeping this mental model will help you remember the flow of file operations.