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Gocyclo calculates cyclomatic complexities of functions in Go source code.

Cyclomatic complexity is a code quality metric which can be used to identify code that needs refactoring. It measures the number of linearly independent paths through a function's source code.

The cyclomatic complexity of a function is calculated according to the following rules:

 1 is the base complexity of a function
+1 for each 'if', 'for', 'case', '&&' or '||'

A function with a higher cyclomatic complexity requires more test cases to cover all possible paths and is potentially harder to understand. The complexity can be reduced by applying common refactoring techniques that lead to smaller functions.


To install the gocyclo command, run

$ go install

and put the resulting binary in one of your PATH directories if $GOPATH/bin isn't already in your PATH.


Calculate cyclomatic complexities of Go functions.
    gocyclo [flags] <Go file or directory> ...

    -over N               show functions with complexity > N only and
                          return exit code 1 if the set is non-empty
    -top N                show the top N most complex functions only
    -avg, -avg-short      show the average complexity over all functions;
                          the short option prints the value without a label
    -ignore REGEX         exclude files matching the given regular expression

The output fields for each line are:
<complexity> <package> <function> <file:line:column>


$ gocyclo .
$ gocyclo main.go
$ gocyclo -top 10 src/
$ gocyclo -over 25 docker
$ gocyclo -avg .
$ gocyclo -top 20 -ignore "_test|Godeps|vendor/" .
$ gocyclo -over 3 -avg gocyclo/

Example output:

9 gocyclo (*complexityVisitor).Visit complexity.go:30:1
8 main main cmd/gocyclo/main.go:53:1
7 gocyclo (*fileAnalyzer).analyzeDecl analyze.go:96:1
4 gocyclo Analyze analyze.go:24:1
4 gocyclo parseDirectives directives.go:27:1
4 gocyclo (Stats).SortAndFilter stats.go:52:1
Average: 2.72

Note that the average is calculated over all analyzed functions, not just the printed ones.

Ignoring individual functions

Individual functions can be ignored with a gocyclo:ignore directive:

func f1() {
	// ...
var f2 = func() {
	// ...


This project is free and open source software licensed under the BSD 3-Clause License.