Tutorial by Examples: u

Using the Package Manager JDK and/or JRE releases for OpenJDK or Oracle can be installed using the package manager on most mainstream Linux distribution. (The choices that are available to you will depend on the distro.) As a general rule, the procedure is to open terminal window and run the comm...

Introduces the definition of an enumeration type. enum Direction { UP, LEFT, DOWN, RIGHT }; Direction d = UP; C++11 In C++11, enum may optionally be followed by class or struct to define a scoped enum. Furthermore, both scoped and unscoped enums can have their unde...

<?xml version="1.0" encoding="utf-8"?> <s:WindowedApplication xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark" xmlns:mx="library://ns.adobe.com/flex/mx"&g...

Suppose you have a pojo class Person public class Person { public String name; public Person(String name) { this.name = name; } } And you want to parse it into a JSON array or a map of Person objects. Due to type erasure you cannot construct classes of List<Person&g...

If we have a file called Business.hs, we can define a Business module that can be import-ed, like so: module Business ( Person (..), -- ^ Export the Person type and all its constructors and field names employees -- ^ Export the employees function ) where -- begin types, function defin...

To export the type and all its constructors, one must use the following syntax: module X (Person (..)) where So, for the following top-level definitions in a file called People.hs: data Person = Friend String | Foe deriving (Show, Eq, Ord) isFoe Foe = True isFoe _ = False This module d...

Haskell supports importing a subset of items from a module. import qualified Data.Stream (map) as D would only import map from Data.Stream, and calls to this function would require D.: D.map odd [1..] otherwise the compiler will try to use Prelude's map function.

When multiple modules define the same functions by name, the compiler will complain. In such cases (or to improve readability), we can use a qualified import: import qualified Data.Stream as D Now we can prevent ambiguity compiler errors when we use map, which is defined in Prelude and Data.Stre...

zip takes two lists and returns a list of corresponding pairs: zip [] _ = [] zip _ [] = [] zip (a:as) (b:bs) = (a,b) : zip as bs > zip [1,3,5] [2,4,6] > [(1,2),(3,4),(5,6)] Zipping two lists with a function: zipWith f [] _ = [] zipWith f _ [] =...

C99 Macros with variadic args: Let's say you want to create some print-macro for debugging your code, let's take this macro as an example: #define debug_print(msg) printf("%s:%d %s", __FILE__, __LINE__, msg) Some examples of usage: The function somefunc() returns -1 if failed and 0 ...

Convert in uppercase the string argument Syntax: UPPER(str) UPPER('fOoBar') -- 'FOOBAR' UCASE('fOoBar') -- 'FOOBAR'

debug() and debugonce() won't work well in the context of most Shiny debugging. However, browser() statements inserted in critical places can give you a lot of insight into how your Shiny code is (not) working. See also: Debugging using browser() Showcase mode Showcase mode displays your app alo...

To concatenate the value of two or more variables into a single string and print it as the output, we need to make use of interpolation. The following Less code, #demo:after { @var1: Hello; @var2: World!!!; content: "@{var1} @{var2}"; } when compiled would set "Hello Wo...

This example draws text paragraphs into any portions of the canvas that have opaque pixels. It works by finding the next block of opaque pixels that is large enough to contain the next specified word and filling that block with the specified word. The opaque pixels can come from any source: Path d...

Classes, structs, enums and all their methods are internal by default. This means they can be only accessed from the same module. The test cases are in a different target an this means they are in a different module. To be able to access the method you want to test, you need to import the module to ...

Some attributes are directly accessible as properties of the element (e.g. alt, href, id, title and value). document.querySelector("a").href = "#top"; Other attributes, including data-attributes can be set as follows: document.querySelector("a").setAttribute("...

To remove an attribute, including directly accessible properties document.querySelector("a").removeAttribute("title"); Data attributes can also be removed as follows (modern browsers): // remove "data-foo" attribute delete document.querySelector("a").dat...

4.0 Since bash 4.0, a new operator ;& was introduced which provides fall through mechanism. #!/bin/bash var=1 case $var in 1) echo "Antartica" ;& 2) echo "Brazil" ;& 3) echo "Cat" ;& esac Outputs: Antartica Brazil Cat ...

4.0 Since Bash 4.0, another operator ;;& was introduced which also provides fall through only if the patterns in subsequent case statement(s), if any, match. #!/bin/bash var=abc case $var in a*) echo "Antartica" ;;& xyz) echo "Brazil" ;;& *b*) ...

Quintile analysis is a common framework for evaluating the efficacy of security factors. What is a factor A factor is a method for scoring/ranking sets of securities. For a particular point in time and for a particular set of securities, a factor can be represented as a pandas series where the in...