McCabe

Thomas McCabe introduced Cyclomatic Complexity, along with Essential Complexity, in his 1976 paper "A Complexity Measure" [1]. Cyclomatic Complexity counts the decision points in a function plus one; Essential Complexity does the same after iteratively replacing well-structured control structures (like if/else and loops) with a single statement, isolating the "unstructured" part of the complexity. See Interpreting Cyclomatic Complexity ↗ for risk-threshold guidance (such as the SEI's commonly cited bands) on reading the values these metrics produce.

McCabe Metrics¶

Notes:

1. Strict Modified Cyclomatic Complexity and Strict Modified Essential Complexity combine both the Strict and Modified adjustments. Understand computes them for convenience, but they aren't named/numbered variants in McCabe's own work, so they're left out of the table above and not tagged as part of this suite.
2. Knot Count (Knots, and its Max/Min essential-complexity variants) measures a related kind of control-flow complexity, but it comes from Woodward, Hennell, and Hedley [2], not McCabe, so it also isn't part of this suite.

Aggregated Values¶

Each metric above is also available summed, maxed, and averaged across a class, file, architecture, or the whole project:

References¶

1. McCabe, Thomas J. "A Complexity Measure." IEEE Transactions on Software Engineering, vol. SE-2, no. 4, 1976, pp. 308-320.
2. Woodward, M.R., M.A. Hennell, and D. Hedley. "A Measure of Control Flow Complexity in Program Text." IEEE Transactions on Software Engineering, vol. SE-5, no. 1, 1979, pp. 45-50.

McCabe Plugins¶