Cyclomatic Complexity

Definition of Cyclomatic Complexity

Cyclomatic complexity is a software metric that measures the complexity of a program by counting the number of linearly independent paths through its source code. Developed by Thomas J. McCabe in 1976, it helps assess how difficult a program is to understand, test, and maintain.

Calculation of Cyclomatic Complexity

The cyclomatic complexity (C) can be calculated using the formula:

C=E−N+2P

Where:

E = Number of edges in the control-flow graph N = Number of nodes in the control-flow graph P = Number of connected components (usually 1 for a single program)

Example of Calculation

For a simple program with:

9 edges 8 nodes 1 connected component

The cyclomatic complexity would be:

C=9−8+2×1=3

Importance of Cyclomatic Complexity

Lower Complexity: Indicates easier readability and maintainability. Higher Complexity: Suggests more potential for errors and difficulties in testing. Testing Strategy: The number of required test cases should equal the cyclomatic complexity to ensure adequate coverage.

A cyclomatic complexity of 10 is often considered a threshold for maintainability. Values above 15 may be acceptable in certain contexts, but should be justified.

Understanding and managing cyclomatic complexity is crucial for improving code quality and reducing the risk of defects in software development.