Tutorial by Examples: r

IMP is a C type referring to the implementation of a method, also known as an implementation pointer. It is a pointer to the start of a method implementation. Syntax: id (*IMP)(id, SEL, …) IMP is defined by: typedef id (*IMP)(id self,SEL _cmd,…); To access this IMP, the message “methodForSe...

When creating a timer, you can set the userInfo parameter to include information that you want to pass to the function you call with the timer. By taking a timer as a parameter in said function, you can access the userInfo property. NSDictionary *dictionary = @{ @&quo...

The HTTP message body can be compressed (since HTTP/1.1). Either by the server compresses the request and adds a Content-Encoding header, or by a proxy does and adds a Transfer-Encoding header. A client may send an Accept-Encoding request header to indicate which encodings it accepts. The most com...

Gson gson = new Gson(); //Create a Gson object MyType target = new MyType(); //This is the object you want to convert to JSON String json = gson.toJson(target); // serializes target to Json MyType target2 = gson.fromJson(json, MyType.class); // deserializes json into target2

Sometimes auto may behave not quite as was expected by a programmer. It type deduces the expression, even when type deduction is not the right thing to do. As an example, when proxy objects are used in the code: std::vector<bool> flags{true, true, false}; auto flag = flags[0]; flags.push_...

While using decorator syntax (with the @) is convenient, it also a bit concealing. You can use properties directly, without decorators. The following Python 3.x example shows this: class A: p = 1234 def getX (self): return self._x def setX (self, value): self._x =...

The fact that the garbage collection will clean up does not mean that you should wait for the garbage collection cycle to clean up. In particular you should not wait for garbage collection to close file handles, database connections and open network connections. for example: In the following code...

Any String can be evaluated at runtime. class Example def self.foo :foo end end eval "Example.foo" #=> :foo

It is possible to compress an HTTP response message body more than once. The encoding names should then be separated by a comma in the order in which they were applied. For example, if a message has been compressed via deflate and then gzip, the header should look like: Content-Encoding: deflate, g...

The client first sends a request with an Accept-Encoding header that indicates it supports gzip: GET / HTTP/1.1\r\n Host: www.google.com\r\n Accept-Encoding: gzip, deflate\r\n \r\n The server may then send a response with a compressed response body and a Content-Encoding header that specifies...

R has a set of built in higher order functions: Map, Reduce, Filter, Find, Position, Negate. Map applies a given function to a list of values: words <- list("this", "is", "an", "example") Map(toupper, words) Reduce successively applies a binary functi...

The objects created within a Tiled Map (.tmx), can be simply loaded as bodies into a Box2D world using the Libgdx MapObject class as following: public void buildBuildingsBodies(TiledMap tiledMap, World world, String layer){ MapObjects objects = tiledMap.getLayers().get(layer).getObjects(); ...

Query SELECT st.name, st.percentage, CASE WHEN st.percentage >= 35 THEN 'Pass' ELSE 'Fail' END AS `Remark` FROM student AS st ; Result +--------------------------------+ | name | percentage | Remark | +--------------------------------+ | Isha | 67 | Pas...

There are a couple of builtin viewports, that each do different things. Here is a list of the names, and their descriptions: Viewport NameDescriptionStretchViewportWill stretch the screen. No black bars, but aspect ratio might be off.FitViewportWill maximize it's size based on the aspect ratio. Cou...

You can make your very own custom viewport. It may have black bars, and it may or may not keep it's aspect ratio, depending on how you program it. A custom viewport would look something like this: public class Tutorial extends Viewport. You would need to override update(width, height), but that's it...

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The <progress> element is new in HTML5 and is used to represent the progress of a task <progress value="22" max="100"></progress> This creates a bar filled 22%

Progress bars can be styled with the progress[value] selector. This example gives a progress bar a width of 250px and a height of 20px progress[value] { width: 250px; height: 20px; } Progress bars can be especially difficult to style. Chrome / Safari / Opera These browsers use the -web...

In Internet Explorer 10+ and Edge, Microsoft provides the -ms-high-contrast media selector to expose the "High Contrast" setting from the browser, which allows the programmer to adjust their site's styles accordingly. The -ms-high-contrast selector has 3 states: active, black-on-white, ...

sqoop import \ --connect <rdbms-jdbc-url> \ --username <username> \ --password <password> \ --table <table-name> Example with Mysql: sqoop import \ --connect jdbc:mysql://mysql.example.com/testdb \ --username root \ --password root \ --table employees CSV file ...