File-handling Pitfalls — File Handling | IGCSE Computer Science

Exam Frequency Analysis

Past paper frequency (2018 to 2024)

This topic accounts for approximately 3% of your exam marks.

stable

Rare

Stable3%

OPENFILE, READFILE, WRITEFILE, CLOSEFILE pseudocode operations appear occasionally.

Common mistakes that lose marks (and lose data in real programs):

Opening a file in WRITE mode when you meant APPEND. Destroys all existing contents.
Forgetting CLOSEFILE. Buffered data may not reach the disk; the file may be incomplete or corrupt.
Reading past the end of file without checking for EOF. Always check using a flag or NOT EOF.
Opening a file that does not exist in READ mode. Causes a runtime error; check it exists first if necessary.
Mixing modes. A single OPENFILE opens for one specific mode. To switch between reading and writing, close and reopen the file.
Forgetting to handle blank lines when reading. An empty line is often the EOF signal in the CIE pseudocode pattern, so be careful with files that genuinely contain blank lines in the middle.
Always make a backup of important text files before writing to them. A program with a bug can wipe out hours of work in milliseconds.