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A code analyzer without caring the C/C++ header files. It works with Java, C/C++, JavaScript, Python, Ruby, Swift, Objective C. Metrics includes cyclomatic complexity number etc.

Project description

Lizard is an extensible Cyclomatic Complexity Analyzer for many programming languages including C/C++ (doesn’t require all the header files or Java imports). It also does copy-paste detection (code clone detection/code duplicate detection) and many other forms of static code analysis.

A list of supported languages:

  • C/C++ (works with C++14)
  • Java
  • C# (C Sharp)
  • JavaScript
  • Objective-C
  • Swift
  • Python
  • Ruby
  • TTCN-3
  • PHP
  • Scala
  • GDScript
  • Golang
  • Lua

By default lizard will search for any source code that it knows and mix all the results together. This might not be what you want. You can use the “-l” option to select language(s).

It counts

  • the nloc (lines of code without comments),
  • CCN (cyclomatic complexity number),
  • token count of functions.
  • parameter count of functions.

You can set limitation for CCN (-C), the number of parameters (-a). Functions that exceed these limitations will generate warnings. The exit code of lizard will be none-Zero if there are warnings.

This tool actually calculates how complex the code ‘looks’ rather than how complex the code really ‘is’. People will need this tool because it’s often very hard to get all the included folders and files right when they are complicated. But we don’t really need that kind of accuracy for cyclomatic complexity.

It requires python2.7 or above (early versions are not verified).

Installation can be used as a stand alone Python script, most functionalities are there. You can always use it without any installation. To acquire all the functionalities of lizard, you will need a proper install.


If you want a proper install:

[sudo] pip install lizard

Or if you’ve got the source:

[sudo] python install --install-dir=/path/to/installation/directory/


lizard [options] [PATH or FILE] [PATH] ...

Run for the code under current folder (recursively):


Exclude anything in the tests folder:

lizard mySource/ -x"./tests/*"


-h, --help            show this help message and exit
--version             show program's version number and exit
                      List the programming languages you want to analyze. if
                      left empty, it'll search for all languages it knows.
                          lizard -l cpp -l java
                      searches for C++ and Java code.
                      The available languages are: cpp, csharp, java,
                      javascript, objectivec, php, python, ruby, swift, ttcn
-V, --verbose         Output in verbose mode (long function name)
-C CCN, --CCN CCN     Threshold for cyclomatic complexity number warning.
                      The default value is 15. Functions with CCN bigger
                      than it will generate warning
-L LENGTH, --length LENGTH
                      Threshold for maximum function length warning. The
                      default value is 1000. Functions length bigger than it
                      will generate warning
                      Limit for number of parameters
-w, --warnings_only   Show warnings only, using clang/gcc's warning format
                      for printing warnings.
-i NUMBER, --ignore_warnings NUMBER
                      If the number of warnings is equal or less than the
                      number, the tool will exit normally, otherwise it will
                      generate error. Useful in makefile for legacy code.
-x EXCLUDE, --exclude EXCLUDE
                      Exclude files that match this pattern. * matches
                      everything, ? matches any single character,
                      "./folder/*" exclude everything in the folder
                      recursively. Multiple patterns can be specified. Don't
                      forget to add "" around the pattern.
--csv                 Generate CSV output as a transform of the default
-X, --xml             Generate XML in cppncss style instead of the tabular
                      output. Useful to generate report in Jenkins server
                      number of working threads. The default value is 1.
                      Using a bigger number can fully utilize the CPU and
                      often faster.
-m, --modified        Calculate modified cyclomatic complexity number,
                      which count a switch/case with multiple cases as
                      one CCN.
                      User the extensions. The available extensions are:
                      -Ecpre: it will ignore code in the #else branch.
                      -Ewordcount: count word frequencies and generate tag
                      cloud. -Eoutside: include the global code as one
                      Sort the warning with field. The field can be nloc,
                      cyclomatic_complexity, token_count, parameter_count,
                      etc. Or an customized file.
                      The path and file name to the whitelist file. It's
                      './whitelizard.txt' by default.

Example use

Analyze a folder recursively: lizard mahjong_game/src

  NLOC    CCN  token  param    function@line@file
    10      2     29      2    start_new_player@26@./html_game.c
     6      1      3      0    set_shutdown_flag@449@./httpd.c
    24      3     61      1    server_main@454@./httpd.c
2 file analyzed.
LOC    Avg.NLOC AvgCCN Avg.ttoken  function_cnt    file
    191     15      3        51        12     ./html_game.c
    363     24      4        86        15     ./httpd.c

!!!! Warnings (CCN > 15) !!!!
    66     19    247      1    accept_request@64@./httpd.c
Total NLOC  Avg.NLOC  Avg CCN  Avg token  Fun Cnt  Warning cnt   Fun Rt   NLOC Rt
       554        20     4.07      71.15       27            1      0.04    0.12

Warnings only (in clang/gcc formation):lizard -w mahjong_game

./src/html_ui/httpd.c:64: warning: accept_request has 19 CCN and 1 params (66 NLOC, 247 tokens)
./src/mahjong_game/mj_table.c:109: warning: mj_table_update_state has 20 CCN and 1 params (72 NLOC, 255 tokens)

Set warning threshold for any field:lizard -T nloc=25

The option -Tcyclomatic_complexity=10 is equal to -C10. The option -Tlength=10 is equal to -L10. The option -Tparameter_count=10 is equal to -a10.

You can also do -Tnloc=10 to set the limit of the NLOC. Any function that has NLOC greater than 10 will generate a warning.

Generated code

Lizard has a simple solution with generated code. Any code in a source file that is following a comment containing “GENERATED CODE” will be ignored completely. The ignored code will not generate any data, except the file counting.

Code Duplicate Detector

lizard -Eduplicate <path to your code>

Generate A Tag Cloud For Your Code

You can generate a “Tag cloud” of your code by the following command. It counts the identifiers in your code (ignoring the comments).

lizard -EWordCount <path to your code>

Using lizard as Python module

You can also use lizard as a Python module in your code:

>>> import lizard
>>> i = lizard.analyze_file("../cpputest/tests/AllTests.cpp")
>>> print i.__dict__
{'nloc': 9, 'function_list': [<lizard.FunctionInfo object at 0x10bf7af10>], 'filename': '../cpputest/tests/AllTests.cpp'}
>>> print i.function_list[0].__dict__
{'cyclomatic_complexity': 1, 'token_count': 22, 'name': 'main', 'parameter_count': 2, 'nloc': 3, 'long_name': 'main( int ac , const char ** av )', 'start_line': 30}

You can also use source code string instead of file. But you need to provide a file name (to identify the language).

>>> i = lizard.analyze_file.analyze_source_code("AllTests.cpp", "int foo(){}")


If for some reason you would like to ignore the warnings, you can use the whitelist. Add ‘whitelizard.txt’ to the current folder (or use -W to point to the whitelist file), then the functions defined in the file will be ignored. Please notice that if you assign the file pathname, it needs to be exactly the same relative path as Lizard to find the file. An easy way to get the file pathname is to copy it from the Lizard warning output. This is an example whitelist:

#The file name can only be whitelizard.txt and put it in the current folder.
#You may have commented lines begin with #.
function_name1, function_name2 # list function names in multiple lines or split with comma.
file/path/name:function1, function2  # you can also specify the filename

Options in Comments

You can use options in the comments of the source code to change the behavior of lizard. By putting “#lizard forgives” inside a function or before a function it will suppress the warning for that function.

int foo() {
    // #lizard forgives the complexity


Lizard requires syntactically correct code. Upon processing input with incorrect or unknown syntax:

  • Lizard guarantees to terminate eventually (i.e., no forever loops, hangs) without hard failures (e.g., exit, crash, exceptions).

  • There is a chance of a combination of the following soft failures:

    • omission
    • misinterpretation
    • improper analysis / tally
    • success (the code under consideration is not relevant, e.g., global macros in C)

This approach makes the Lizard implementation simpler and more focused with partial parsers for various languages. Developers of Lizard attempt to minimize the possibility of soft failures. Hard failures are bugs in Lizard code, while soft failures are trade-offs or potential bugs.

In addition to asserting the correct code, Lizard may choose not to deal with some advanced or complicated language features:

  • C/C++ digraphs and trigraphs are not recognized.
  • C/C++ preprocessing or macro expansion is not performed. For example, using macro instead of parentheses (or partial statements in macros) can confuse Lizard’s bracket stacks.
  • Some C++ complicated templates may cause confusion with matching angle brackets and processing less-than < or more-than > operators inside of template arguments.

Literatures Referring to Lizard

Lizard is often used in software related researches. If you used it to support your work, you may contact the lizard author to add your work in the following list.

Lizard is also used as a plugin for fastlane to help check code complexity and submit xml report to sonar.

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