Tutorial by Examples: g

Download and install Visual Studio. Visual Studio can be downloaded from VisualStudio.com. The Community edition is suggested, first because it is free, and second because it involves all the general features and can be extended further. Open Visual Studio. Welcome. Go to File → New ...

Consider following DOM Structure <ul class="parentUl"> <li> Level 1 <ul class="childUl"> <li>Level 1-1 <span> Item - 1 </span></li> <li>Level 1-1 <span> Item - 2 </span></li&gt...

SharedPreferences sharedPreferences = ...; sharedPreferences.registerOnSharedPreferenceChangeListener(mOnSharedPreferenceChangeListener); private final SharedPreferences.OnSharedPreferenceChangeListener mOnSharedPreferenceChangeListener = new SharedPreferences.OnSharedPreferenceChangeListener(...

To find a match, the regex engine will consume characters one by one. When a partial match begins, the engine will remember the start position so it can go back in case the following characters don't complete the match. If the match is complete, the is no backtracking If the match isn't complete...

Backtracking can be caused by optional quantifiers or alternation constructs, because the regex engine will try to explore every path. If you run the regex a+b against aaaaaaaaaaaaaa there is no match and the engine will find it pretty fast. But if you change the regex to (aa*)+b the number of comb...

The function in_array() returns true if an item exists in an array. $fruits = ['banana', 'apple']; $foo = in_array('banana', $fruits); // $foo value is true $bar = in_array('orange', $fruits); // $bar value is false You can also use the function array_search() to get the key of a specifi...

Govendor is a tool that is used to import 3rd party packages into your code repository in a way that is compatible with golang's vendoring. Say for example that you are using a 3rd party package bosun.org/slog: package main import "bosun.org/slog" func main() { slog.Infof(&quo...

A flags-style enum value needs to be tested with bitwise logic because it may not match any single value. [Flags] enum FlagsEnum { Option1 = 1, Option2 = 2, Option3 = 4, Option2And3 = Option2 | Option3; Default = Option1 | Option3, } The Default value is actually a ...

NSAttributedString (and its mutable sibling NSMutableAttributedString) allows you to create strings that are complex in their appearance to the user. A common application is to use this to display a string and adding custom kerning / letter-spacing. This would be achieved as follows (where label ...

Method overloading, also known as function overloading, is the ability of a class to have multiple methods with the same name, granted that they differ in either number or type of arguments. Compiler checks method signature for method overloading. Method signature consists of three things - Met...

Method overriding is the ability of subtypes to redefine (override) the behavior of their supertypes. In Java, this translates to subclasses overriding the methods defined in the super class. In Java, all non-primitive variables are actually references, which are akin to pointers to the location of...

use Data::Dumper; my $data_structure = { foo => 'bar' }; print Dumper $data_structure; Using Data::Dumper is an easy way to look at data structures or variable content at run time. It ships with Perl and you can load it easily. The Dumper function returns the data structure serialized in a...

Sometimes Data::Dumper is not enough. Got a Moose object you want to inspect? Huge numbers of the same structure? Want stuff sorted? Colored? Data::Printer is your friend. use Data::Printer; p $data_structure; Data::Printer writes to STDERR, like warn. That makes it easier to find the outpu...

Using reflection, a method of an object can be invoked during runtime. The example shows how to invoke the methods of a String object. import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; String s = "Hello World!"; // method without parameters // i...

The docker rmi command is used to remove images: docker rmi <image name> The full image name must be used to remove an image. Unless the image has been tagged to remove the registry name, it needs to be specified. For example: docker rmi registry.example.com/username/myAppImage:1.3.5 I...

Often, we need to perform an operation over every element in a variadic template parameter pack. There are many ways to do this, and the solutions get easier to read and write with C++17. Suppose we simply want to print every element in a pack. The simplest solution is to recurse: C++11 void print...

XML is made of basic building blocks, which are: element text attributes comments processing instructions An element has angle brackets: <element/> <element>some content</element> An attribute appears in an opening element tag: <element attribute-name="...

docker run --restart=always -d <container> By default, Docker will not restart containers when the Docker daemon restarts, for example after a host system reboot. Docker provides a restart policy for your containers by supplying the --restart command line option. Supplying --restart=always ...

Const ForReading = 1 Const ForWriting = 2 Const ForAppending = 8 Sub FsoExample() Dim fso As Object ' declare variable Set fso = CreateObject("Scripting.FileSystemObject") ' Set it to be a File System Object ' now use it to check if a file exists Dim myFilePath A...

Const ForReading = 1 Const ForWriting = 2 Const ForAppending = 8 Sub ReadTextFileExample() Dim fso As Object Set fso = CreateObject("Scripting.FileSystemObject") Dim sourceFile As Object Dim myFilePath As String Dim myFileText As String myFilePath = &...