Another more interesting approach is to study a known and\u00a0mature\u00a0open source project to discover how their developers implements the code. In case of C language a good candidate could be\u00a0the \u00a0SQLite<\/a>\u00a0source code.<\/p>\n What’s interesting with SQLite is that it’s accessible even\u00a0for the beginner C developers, its contributors use very basic coding rules, what makes it very easy to understand and maintain.<\/p>\n Let\u2019s go inside the SQLite\u00a0source code using\u00a0CppDepend\u00a0<\/a>and discover some basic coding rules adopted by their developers.<\/p>\n Encapsulation<\/strong><\/p>\n Encapsulation \u00a0is the hiding of functions and data which are internal to an implementation. \u00a0In C, encapsulation is performed by using the static keyword . These entities are called file-scope functions and variables.<\/p>\n Let\u2019s search for all static functions by executing the following CQLinq query<\/p>\n We can use the Metric view to\u00a0have a good idea how many functions are concerned. In the Metric View, the code base is represented through a Treemap. Treemapping is a method for displaying tree-structured data by using nested rectangles. The tree structure used in a CppDepend treemap is the usual code hierarchy:<\/p>\n The treemap view provides a useful way to represent the result of a CQLinq request, and for the previous request \u00a0the static\u00a0methods are the not greyed ones.<\/p>\n As we can observe many functions are declared as static.<\/p>\n Use structs to store your data model<\/strong><\/p>\n In C programing the functions uses variables to acheive their treatments, theses variables could be:<\/p>\n Each project has it\u2019s data model which could be used by many source files, using global variables is a solution but not the good one, using structs to group data is more recommended.<\/p>\n Let\u2019s search for defined structs:<\/p>\n Many structs are used to specify the data model.<\/p>\n Let function be short and sweet<\/strong><\/p>\n Here\u2019s from the\u00a0linux coding style web page<\/a>, an\u00a0advice about the length of functions:<\/p>\n \u00a0Let\u2019s search for functions where the number of lines of code is less\u00a0than 30<\/p>\n More than 90% of functions\u00a0has less \u00a0than 30 lines of code.<\/p>\n Function Number of parameters<\/strong><\/p>\n Functions\u00a0where NbParameters > 8\u00a0might be painful to call \u00a0and might degrade performance. Another alternative is to provide \u00a0a structure dedicated to handle arguments passing.<\/p>\n only few\u00a0methods has more than 8 parameters.<\/p>\n Number of\u00a0local variables<\/strong><\/p>\n Methods where NbVariables is higher than 8 are hard to understand and maintain. Methods where NbVariables is higher than 15 are extremely complex and should be split in smaller methods (except if they are automatically generated by a tool).<\/p>\n only few\u00a0functions has more than 15 local variables.<\/p>\n Avoid defining complex functions<\/strong><\/p>\n Many metrics exist to detect complex functions, NBLinesOfCode,Number of parameters and number of local variables are the basic ones.<\/p>\n There are other interesting metrics to detect complex functions:<\/p>\n The max value tolerated for these metrics depends more on the team choices, there\u2019s no standard values.<\/p>\n Let\u2019s search for functions candidate to be refactored:<\/p>\n <\/p>\n only very few functions could be considered as complex.<\/p>\n Be Const Correct<\/strong><\/p>\n C provides the\u00a0<\/span>const<\/em>\u00a0key word to allow passing as parameters objects that cannot change to indicate when a method doesn’t modify its object. Using const in all the right places is called “const correctness.” It’s hard at first, but using const really tightens up your coding style.\u00a0<\/span><\/p>\n Let’s search for functions having at least one const parameter:<\/p>\n Function coupling<\/strong><\/p>\n Functions using many other ones are very difficult to understand and maintain. It’s recommended \u00a0to minimize the efferent coupling of your functions.<\/p>\n For SQLite very few functions have\u00a0a high efferent coupling:<\/p>\n If you can exit a function early, you should.<\/strong><\/p>\n Early exits out of a function, specially through guard clauses at the top of a function are preferred since they simplify the logic further down in the function.<\/span><\/p>\n In the SQLite source code this best practice rule is applied for almost all the functions.<\/p>\n What’s not recommended from the sqlite implementation<\/strong><\/p>\n The sqlite3.c file contains many functions, structs and variables which is not recommended. However Sqlite3 is designed to be embedded in other projects and it’s very practical to have one file to embed.<\/p>\n Conclusion<\/strong><\/p>\n Exploring some known open source projects is always good to elevate your programming skills, no need to download and build the project, you can just discover the code from GitHub.<\/p>\n <\/p>\n","protected":false},"excerpt":{"rendered":" Many resources exist talking about the better way to\u00a0learn a programming language, we can enumerate: Reading a book or a magazine. Web sites. From a collegue. Doing a training. Another more interesting approach is to study a known and\u00a0mature\u00a0open source project to discover how their developers implements the code. In case of C language a … Continue reading “Learn the “C” programming language by studying real projects: SQLite case study”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[],"tags":[],"class_list":["post-1918","post","type-post","status-publish","format-standard","hentry"],"_links":{"self":[{"href":"https:\/\/codergears.com\/Blog\/index.php?rest_route=\/wp\/v2\/posts\/1918","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/codergears.com\/Blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/codergears.com\/Blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/codergears.com\/Blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/codergears.com\/Blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1918"}],"version-history":[{"count":21,"href":"https:\/\/codergears.com\/Blog\/index.php?rest_route=\/wp\/v2\/posts\/1918\/revisions"}],"predecessor-version":[{"id":1997,"href":"https:\/\/codergears.com\/Blog\/index.php?rest_route=\/wp\/v2\/posts\/1918\/revisions\/1997"}],"wp:attachment":[{"href":"https:\/\/codergears.com\/Blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1918"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/codergears.com\/Blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1918"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/codergears.com\/Blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1918"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"linux17\"](\"http:\/\/www.codergears.com\/Blog\/wp-content\/uploads\/linux17.png\")
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<\/a><\/p>\nFunctions should be short and sweet, and do just one thing. They should\r\nfit on one or two screenfuls of text (the ISO\/ANSI screen size is 80x24,\r\nas we all know), and do one thing and do that well.\r\n\r\nThe maximum length of a function is inversely proportional to the\r\ncomplexity and indentation level of that function. So, if you have a\r\nconceptually simple function that is just one long (but simple)\r\ncase-statement, where you have to do lots of small things for a lot of\r\ndifferent cases, it's OK to have a longer function.<\/pre>\n
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