Tutorial by Examples: l

The base package parallel allows parallel computation through forking, sockets, and random-number generation. Detect the number of cores present on the localhost: parallel::detectCores(all.tests = FALSE, logical = TRUE) Create a cluster of the cores on the localhost: parallelCluster <- para...

If there are sections of code that you are considering removing or want to temporarily disable, you can comment it out with a block comment. /* Block comment around whole function to keep it from getting used. * What's even the purpose of this function? int myUnusedFunction(void) { int i =...

If MsgBox("Click OK") = vbOK Then can be used in place of If MsgBox("Click OK") = 1 Then in order to improve readability. Use Object Browser to find available VB constants. View → Object Browser or F2 from VB Editor. Enter class to search View members available ...

Descriptive names and structure in your code help make comments unnecessary Dim ductWidth As Double Dim ductHeight As Double Dim ductArea As Double ductArea = ductWidth * ductHeight is better than Dim a, w, h a = w * h This is especially helpful when you are copying data from one ...

Good error handling prevents end users from seeing VBA runtime errors and helps the developer easily diagnose and correct errors. There are three main methods of Error Handling in VBA, two of which should be avoided for distributed programs unless specifically required in the code. On Error GoTo 0...

The .GetValueOrDefault() method returns a value even if the .HasValue property is false (unlike the Value property, which throws an exception). class Program { static void Main() { int? nullableExample = null; int result = nullableExample.GetValueOrDefault(); C...

When filtering an email address filter_var() will return the filtered data, in this case the email address, or false if a valid email address cannot be found: var_dump(filter_var('[email protected]', FILTER_VALIDATE_EMAIL)); var_dump(filter_var('notValidEmail', FILTER_VALIDATE_EMAIL)); Results: ...

When filtering a value that should be an integer filter_var() will return the filtered data, in this case the integer, or false if the value is not an integer. Floats are not integers: var_dump(filter_var('10', FILTER_VALIDATE_INT)); var_dump(filter_var('a10', FILTER_VALIDATE_INT)); var_dump(filt...

When validating that an integer falls in a range the check includes the minimum and maximum bounds: $options = array( 'options' => array( 'min_range' => 5, 'max_range' => 10, ) ); var_dump(filter_var('5', FILTER_VALIDATE_INT, $options)); var_dump(filter_var('...

When filtering a URL filter_var() will return the filtered data, in this case the URL, or false if a valid URL cannot be found: URL: example.com var_dump(filter_var('example.com', FILTER_VALIDATE_URL)); var_dump(filter_var('example.com', FILTER_VALIDATE_URL, FILTER_FLAG_SCHEME_REQUIRED)); var_du...

In PHP 5.3+ and above you can utilize late static binding to control which class a static property or method is called from. It was added to overcome the problem inherent with the self:: scope resolutor. Take the following code class Horse { public static function whatToSay() { echo ...

C++11 C++11 introduces two new special member functions: the move constructor and the move assignment operator. For all the same reasons that you want to follow the Rule of Three in C++03, you usually want to follow the Rule of Five in C++11: If a class requires ONE of five special member functions...

C++11 We can combine the principles of the Rule of Five and RAII to get a much leaner interface: the Rule of Zero: any resource that needs to be managed should be in its own type. That type would have to follow the Rule of Five, but all users of that resource do not need to write any of the five sp...

const auto input = "Some people, when confronted with a problem, think \"I know, I'll use regular expressions.\""s; smatch sm; cout << input << endl; // If input ends in a quotation that contains a word that begins with "reg" and another word begining...

This code takes in various brace styles and converts them to One True Brace Style: const auto input = "if (KnR)\n\tfoo();\nif (spaces) {\n foo();\n}\nif (allman)\n{\n\tfoo();\n}\nif (horstmann)\n{\tfoo();\n}\nif (pico)\n{\tfoo(); }\nif (whitesmiths)\n\t{\n\tfoo();\n\t}\n"s; cout &lt...

A std::regex_token_iterator provides a tremendous tool for extracting elements of a Comma Separated Value file. Aside from the advantages of iteration, this iterator is also able to capture escaped commas where other methods struggle: const auto input = "please split,this,csv, ,line,\\,\n&quot...

When processing of captures has to be done iteratively a regex_iterator is a good choice. Dereferencing a regex_iterator returns a match_result. This is great for conditional captures or captures which have interdependence. Let's say that we want to tokenize some C++ code. Given: enum TOKENS { ...

Single node Installation Pre-install NodeJS, Python and Java Select your installation document based on your platform http://docs.datastax.com/en/cassandra/3.x/cassandra/install/installTOC.html Download Cassandra binaries from http://cassandra.apache.org/download/ Untar the downloaded file to ...

Deletes all documents matching the query parameter: // New in MongoDB 3.2 db.people.deleteMany({name: 'Tom'}) // All versions db.people.remove({name: 'Tom'}) Or just one // New in MongoDB 3.2 db.people.deleteOne({name: 'Tom'}) // All versions db.people.remove({name: 'Tom'}, true) M...

You can nest lists to represent sub-items of a list item. <ul> <li>item 1</li> <li>item 2 <ul> <li>sub-item 2.1</li> <li>sub-item 2.2</li> </ul> </li> <li>item 3</li> </ul> ...