Debugging

Debugging is the process of identifying and fixing errors (bugs) in an algorithm or program. It is distinct from evaluation: evaluation checks whether an algorithm is logically correct before it runs; debugging diagnoses what went wrong after a fault has been observed.

Types of Errors

Syntax errors — the code violates the language's grammar rules and will not run at all. These are caught by the compiler or interpreter.

Logic errors — the code runs without crashing but produces wrong results. These are the hardest to catch because the program appears to work. A dry run (tracing the algorithm step by step with test inputs) is the primary tool for catching logic errors before they reach production.

Runtime errors — the code runs but crashes during execution (e.g., dividing by zero, accessing a null value). These are caught only when the specific path is executed.

Debugging and Evaluation

evaluation and debugging are the two sides of the same quality problem. Evaluation happens before coding — it is the dry-run pass that catches errors on paper. Debugging happens after coding — it is the process of tracing errors that survived to implementation. The relationship between them reflects the fail-early principle: faults caught on paper cost minutes; faults caught in production cost hours or worse.

Sources

• what-is-evaluation-bbc-bitesize
• evaluation
• algorithm