Tutorial by Examples: r

std::this_thread is a namespace which has functions to do interesting things on the current thread from function it is called from. FunctionDescriptionget_idReturns the id of the threadsleep_forSleeps for a specified amount of timesleep_untilSleeps until a specific timeyieldReschedule running threa...

What are Array-like Objects? JavaScript has "Array-like Objects", which are Object representations of Arrays with a length property. For example: var realArray = ['a', 'b', 'c']; var arrayLike = { 0: 'a', 1: 'b', 2: 'c', length: 3 }; Common examples of Array-like Objects...

To get info from the requesting url (notice that req is the request object in the handler function of routes). Consider this route definition /settings/:user_id and this particular example /settings/32135?field=name // get the full path req.originalUrl // => /settings/32135?field=name // get...

Unlike the WHERE clause, HAVING can be used with aggregate functions. An aggregate function is a function where the values of multiple rows are grouped together as input on certain criteria to form a single value of more significant meaning or measurement (Wikipedia). Common aggregate function...

The STUFF() function inserts a string into another string by first deleting a specified number of characters. The following example, deletes "Svr" and replaces it with "Server". This happens by specifying the start_position and length of the replacement. SELECT STUFF('SQL Svr D...

Apple's Reachability class periodically checks the network status and alerts observers to changes. Reachability *internetReachability = [Reachability reachabilityForInternetConnection]; [internetReachability startNotifier];

Reachability uses NSNotification messages to alert observers when the network state has changed. Your class will need to become an observer. [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(reachabilityChanged:) name:kReachabilityChangedNotification object:nil]; Elsewher...

- (void)reachabilityChanged:(NSNotification *)note { Reachability* reachability = [note object]; NetworkStatus netStatus = [reachability currentReachabilityStatus]; if (netStatus == NotReachable) { NSLog(@"Network unavailable"); } }

- (void)reachabilityChanged:(NSNotification *)note { Reachability* reachability = [note object]; NetworkStatus netStatus = [reachability currentReachabilityStatus]; switch (netStatus) { case NotReachable: NSLog(@"Network unavailable"); br...

Many IDEs provide support for generating HTML from Javadocs automatically; some build tools (Maven and Gradle, for example) also have plugins that can handle the HTML creation. However, these tools are not required to generate the Javadoc HTML; this can be done using the command line javadoc tool. ...

Functional Interfaces Lambdas can only operate on a functional interface, which is an interface with just one abstract method. Functional interfaces can have any number of default or static methods. (For this reason, they are sometimes referred to as Single Abstract Method Interfaces, or SAM Interf...

This example demonstrates how Angular expressions are evaluated when using type="text" and type="number" for the input element. Consider the following controller and view: Controller var app = angular.module('app', []); app.controller('ctrl', function($scope) { $sco...

5 Object.freeze makes an object immutable by preventing the addition of new properties, the removal of existing properties, and the modification of the enumerability, configurability, and writability of existing properties. It also prevents the value of existing properties from being changed. Howev...

You can create an HTML`...` template string tag function to automatically encodes interpolated values. (This requires that interpolated values are only used as text, and may not be safe if interpolated values are used in code such as scripts or styles.) class HTMLString extends String { static e...

// Java: String joined = things.stream() .map(Object::toString) .collect(Collectors.joining(", ")); // Kotlin: val joined = things.joinToString() // ", " is used as separator, by default

// Java: int total = employees.stream() .collect(Collectors.summingInt(Employee::getSalary))); // Kotlin: val total = employees.sumBy { it.salary }

// Java: Map<Department, List<Employee>> byDept = employees.stream() .collect(Collectors.groupingBy(Employee::getDepartment)); // Kotlin: val byDept = employees.groupBy { it.department }

// Java: Map<Department, Integer> totalByDept = employees.stream() .collect(Collectors.groupingBy(Employee::getDepartment, Collectors.summingInt(Employee::getSalary))); // Kotlin: val totalByDept = employees.groupBy { it.dept }.mapValues { it.v...

// Java: Map<Boolean, List<Student>> passingFailing = students.stream() .collect(Collectors.partitioningBy(s -> s.getGrade() >= PASS_THRESHOLD)); // Kotlin: val passingFailing = students.partition { it.grade >= PASS_THRESHOLD }

// Java: List<String> namesOfMaleMembersCollect = roster .stream() .filter(p -> p.getGender() == Person.Sex.MALE) .map(p -> p.getName()) .collect(Collectors.toList()); // Kotlin: val namesOfMaleMembers = roster.filter { it.gender == Person.Sex.MALE }.map { it.nam...