Understanding Cyclomatic Complexity NDepend

If we take I2 and add and ‘if’ statement , the complexity is incremented because a single ‘if’ statement has a complexity of 1. McCabe is not adapted to measure the complexity of the software architecture. Or, to say it differently, it does not work on a complex C++/C# design pattern which splits the complexity over several classes.

It is important in designing test cases because it reveals the different paths or scenarios a program can take . “To have good testability and maintainability, McCabe recommends that no program module should exceed a cyclomatic complexity of 10″(Marsic,2012, p. 232). In fact it’s a measure of code complexity used in software development to point out more complex parts of code . You can calculate it using the E-N+2P formula, but I would suggest you have this calculated automatically by a plugin. I have heard of a rule of thumb that you should strive to keep the CC below 5 to maintain good readability and maintainability of your code.

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First and foremost, you might start to wonder if this isn’t all a bit reductionist. I have no doubt that you could conceive of a method with a high cyclomatic complexity score that’s also relatively what is cyclomatic complexity easy to understand, test, and maintain. Reducing a method to its decision points provides interesting but incomplete data about that method. He did, however, give it an intimidating-sounding name.

definition of cyclomatic complexity

It is not necessary for management to produce an edict that all code must be 100% covered at all times, and yet at the same time this is the goal. We recommend checking for cognitive complexity rather than cyclomatic complexity, and we pair that with a return statements check, as two of our 10 point maintainability inspection. 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.

FAQs on Cyclomatic Complexity

In other words, this class was a clear example of Insufficient Modularization. When she approached her team members, she realized that they were already aware of the size and complexity of this class. In fact, she also came to know that this class was prone to defects and was subjected to frequent changes.

definition of cyclomatic complexity

It is computed using the Control Flow Graph of the program. The nodes in the graph indicate the smallest group of commands of a program, and a directed edge in it connects the two nodes i.e. if the second command might immediately follow the first command. Section VI of McCabe’s 1976 paper is concerned with determining what the control-flow graphs of non-structured programs look like in terms of their subgraphs, which McCabe identifies. McCabe called the measure he devised for this purpose essential complexity. Consider the control flow graph of your function, with an additional edge running from the exit to the entrance. The cyclomatic complexity is the maximum number of cuts we can make without separating the graph into two pieces.

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It is a quantitative measure of the number of linearly independent paths through a program’s source code. A quantitative measure of the number of linearly independent paths through a program’s source code which indicates the complexity of a program or a function. The cyclomatic complexity is a measurement of the code complexity proposed by Thomas J. McCabe which is often considered as a magic number https://www.globalcloudteam.com/ which allows us to measure the complexity of a program. It is common to say that a function with a cyclomatic complexity higher than 10 is difficult to maintain due to an over-reliance on branches, switch/cases or loops. These functions are often a good candidate for a redesign. Cyclomatic complexity is a source code complexity measurement that is being correlated to a number of coding errors.

definition of cyclomatic complexity

Will be equal to the number of programs in question, as each subprogram will appear as a disconnected subset of the graph. The amount of complexity in a program is often determined by the amount of time and effort that went into it. The more complex the system, the more difficult it will be for changes to be made without disrupting other parts of the system. I believe it’s generally considered in the context of a maintainability index. The more branches there are within a particular method, the more difficult it is to maintain a mental model of that method’s operation . Learn how to reduce the complexity of your code — and maintain a readable codebase — by using a static code analyzer such as Helix QAC.

Analysis Configuration

McCabe’s cyclomatic complexity is a simple and intuitive metric that allows us achieve reliable results at the function level. It does not cover all kinds of software complexity but it allows us to clearly identify functions with a lot of loops, selection statements and switch/cases. That’s why we have also included it in Squish Coco v4.2 and above. Cyclomatic complexity can be calculated manually if the program is small. Automated tools need to be used if the program is very complex as this involves more flow graphs.

  • And that matters because complexity translates directly to risk, a concern of interest both to the business and to developers.
  • For the most part, complexity under 6 to 8 is probably fine as long as the code itself is well formatted.
  • Thomas J. McCabe Sr. developed this metric, first describing it in a 1976 paper.
  • Because if you don’t, sooner or later at wave of management or consultants will.
  • It is a quantitative measure of independent paths in the source code of a software program.
  • Boolean operators can add either one or nothing to complexity.
  • And the methodology by which this polling is conducted varies.

Once the basic set is formed, TEST CASES should be written to execute all the paths. Independent path is defined as a path that has at least one edge which has not been traversed before in any other paths. For starters, bear in mind that you don’t actually need to calculate it. The IDE you use to code most likely already has this functionality built in. In this, nested conditional structures are harder to understand than non-nested structures.

Cyclomatic Complexity Example 1

They should be easy to understand regardless of your language preferences. Often, code review can take cyclomatic complexity into account, even flagging problematic functions that may need manual review. This can make it a very useful tool for maintaining a clean and orderly codebase.

E is the number of edges of the graph, N is the number of nodes and M is McCabe’s complexity. This finding suggests that a better identification of anti-patterns can be achieved with a combined technique using a mix of historical and structural properties. These results suggest that the presence of anti-patterns in source code is sometimes tolerable, and part of developers’ design choices. Code without unit tests is much more difficult to refactor with confidence, and when it does get modified the risk of introducing a new bug is high.

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The following C program fragment has an essential complexity of four; its CFG is irreducible. The program finds the first row of z which is all zero and puts that index in i; if there is none, it puts -1 in i. For instance, strategy can help you reduce the need for if statements. The template method can help you get rid of code duplication. Flag arguments necessarily introduce more complexity due to the need for decision structures.