It is calculated by developing a Control Flow Graph of the code that measures the number of linearly-independent paths through a program module. Cyclomatic complexity is a software metric used to indicate the complexity of a program. It is a quantitative measure of the number of linearly independent paths through a program’s source code. If the program/ source code does not have any loop or no control flow statement, then the cyclomatic complexity is 1. If the program/ source code encounters any loop, the complexity increases accordingly.

It is higher when there are more decision points, branches, loops or nested loops in the function. However, this is true only for decision points counted at the lowest, machine-level instructions. Decisions involving compound predicates like those found in high-level languages like IF cond1 AND cond2 THEN … Should be counted in terms of predicate variables involved, i.e. in this example one should count two decision points, because at machine level it is equivalent to IF cond1 THEN IF cond2 THEN …. Besides tools measuring different things for the same metric , the main obstacle is the interpretation of the results. The simple interpretation is that the cyclomatic complexity is an upper bound for the number of test cases required to obtain branch coverage of the code.

## Lower Cyclomatic Complexity = Better Code

For instance, a function with a https://www.globalcloudteam.com/ of 1 will always go through the same execution path. Conversely, a function with a cyclomatic complexity value of 8 will have eight possible execution paths. Cyclomatic complexity measures the number of times you must execute a block of code with varying parameters in order to execute every path through that block. A higher count is bad because it increases the chances for logical errors escaping your testing strategy. There are many reasons why it’s a good idea to remove obsolete—i.e., dead—code from your application.

Statement or other control block like a loop, cyclomatic complexity goes up, since the graph will look more and more like a tree. Cyclomatic Complexity is a code metric that you can view in many IDEs like Visual Studio. While it’s not an exact science, it allows you to get a general idea of the complexity of functions, classes, and namespaces, which can be useful when looking for code to refactor. Cyclomatic Complexity is software metric useful for structured or White Box Testing. If the decision points are more, then complexity of the program is more.

## Reduce Code Complexity, Increase Code Clarity

The exit has been connected to the entry to make the graph strongly connected. However, the relationship of cyclomatic complexity with cognitive complexity isn’t always that clear-cut. It’s possible to have methods with high cyclomatic complexity that are easy to understand. Cyclomatic complexity is a metric that indicates the possible number of paths inside a code artifact, e.g., a function, class, or whole program. Thomas J. McCabe Sr. developed this metric, first describing it in a 1976 paper. One of the reasons for using metrics like cyclomatic complexity is that in general a human being can only keep track of about 7 pieces of information simultaneously in your brain.

In the case of simple comparisons and decision structures, it may give a misleading figure. In this, nested conditional structures are harder to understand than non-nested structures. It is used to measure the minimum effort and best areas of concentration for testing.

## Software Testing

The metric itself is based on graph measures on the control flow graph of a method and describes the non-linearity of this graph. For structured programming the metric is roughly equivalent to one plus the number of loops and if statements. what is cyclomatic complexity is a source code complexity measurement that is being correlated to a number of coding errors.

- Since it’s just perfectly linear code, the number of nodes will cancel out the number of edges, giving a cyclomatic complexity of one.
- I believe it’s generally considered in the context of a maintainability index.
- It is used to measure the minimum effort and best areas of concentration for testing.
- The examples will be in C# for the simple reason that it’s my go-to language.
- Some complexity calculation tools are used for specific technologies.
- Cyclomatic complexity can be calculated by using control flow graphs or with respect to functions, modules, methods or classes within a software program.

Mathematically, for a structured program, the directed graph inside the control flow is the edge joining two basic blocks of the program as control may pass from first to second. Another application of cyclomatic complexity is in determining the number of test cases that are necessary to achieve thorough test coverage of a particular module. Nesting statements tends to expand the context that a developer has to understand for changing a line. But this does not imply that we cannot measure and control complexity. It just has to be done with multiple metrics and checks that cover the various aspects of complexity.

## Cyclomatic Complexity Examples

You’re likelier to introduce defects to an area of the codebase that you change a lot than to one you rarely touch. In addition, the more complex a given piece of code is, the more likely you are to misunderstand it and introduce a defect to it. Understanding cyclomatic complexity doesn’t have to be complex.

It can be used as a quality metric, given the relative complexity of various designs. The set of all even subgraphs of a graph is closed under symmetric difference, and may thus be viewed as a vector space over GF; this vector space is called the cycle space of the graph. The cyclomatic number of the graph is defined as the dimension of this space.

## Cyclomatic complexity

For instance, you could create a new function, maintaining the old one as it is and extracting the common parts into its own private function. All else being equal, smaller functions are easier to read and understand. They’re also less likely to contain bugs by virtue of their length. You may be sent directly into the five stages of grief at the result. For the most part, complexity under 6 to 8 is probably fine as long as the code itself is well formatted.

Since GF has two elements and the cycle space is necessarily finite, the cyclomatic number is also equal to the 2-logarithm of the number of elements in the cycle space. Get a quick notification when we blog about software quality, speak on conferences or publish our CQSE Spotlight. Another metric we like to look at is nesting depth, which is the maximal number of control structures that are nested in each other.

## Avoid Flag Arguments in Functions

In this case, the fix was simple — the coroutine has a bunch of tasks to do, so I break those tasks up into smaller coroutines, and replace the main method with calls to subroutines. The overall code didn’t change, and neither did the total complexity of the class itself, but now the main function isn’t a 400 line monstrosity. Visual Studio and other IDEs will calculate aggregate complexities of entire classes and namespaces, which can be useful for tracking down your most complex classes.