Halstead complexity measures are software metrics introduced by Maurice Howard Halstead in 1977[1] as part of his treatise on establishing an empirical science of software development. Halstead makes the observation that metrics of the software should reflect the implementation or expression of algorithms in different languages, but be independent of their execution on a specific platform. These metrics are therefore computed statically from the code.
Halstead's goal was to identify measurable properties of software, and the relations between them. This is similar to the identification of measurable properties of matter (like the volume, mass, and pressure of a gas) and the relationships between them (such as the gas equation). Thus his metrics are actually not just complexity metrics.
Calculation
First we need to compute the following numbers, given the program:
- = the number of distinct operators
- = the number of distinct operands
- = the total number of operators
- = the total number of operands
From these numbers, five measures can be calculated:
- Program length:
- Program vocabulary:
- Volume:
- Difficulty :
- Effort:
The difficulty measure is related to the difficulty of the program to write or understand, e.g. when doing code review.
References
- ^ Halstead, Maurice H. (1977). Elements of Software Science. Amsterdam: Elsevier North-Holland, Inc. ISBN 0-444-00205-7.
See also
External links
- The Halstead metrics - Extensive discussion on the calculation and use of Halstead Metrics in an object-oriented environment (with specific reference to Java).
- Calculation of Halstead metrics - Measurement of Halstead Metrics.
- [1] - Maintainability Index in Microsoft's Visual Studio and its relation to the Halstead complexity measure