Tutorial by Examples: u

In Insert mode, press <C-r> and then % to insert the filename. This technique is applicable to all registers. For e.g. if in insert mode, you want to paste the current search pattern, you can type <C-r> and then /.

Sometimes it's useful to be able to extend a class with new functions. For example let's suppose that a string should be converted to a camel case string. So we need to tell TypeScript, that String contains a function called toCamelCase, which returns a string. interface String { toCamelCase()...

While running any web application it’s necessary to take loading time into consideration. If your code tries to access any element that is not yet loaded, WebDriver will throw an exception and your script will stop. There are three types of Waits - Implicit Waits Explicit Waits Fluent Waits ...

In Racket, we use recursion very frequently. Here is an example of a function that sums all of the numbers from zero to the parameter, n. (define (sum n) (if (zero? n) 0 (+ n (sum (sub1 n))))) Note that there are many helpful convenience based functions used here, such as ...

# list gem sources: gem sources -l # remove default gem source: gem sources -r https://rubygems.org/ # add other gem sources: gem sources -a https://ruby.taobao.org/

Mostly used under ng-repeat ngValue is useful when dynamically generating lists of radio buttons using ngRepeat <script> angular.module('valueExample', []) .controller('ExampleController', ['$scope', function($scope) { $scope.names = ['pizza', 'unicorns', 'robots']; ...

Overall the easiest way to work with JSON is to have a case class mapping directly to the JSON (same fields name, equivalent types, etc.). case class Person( name: String, age: Int, hobbies: Seq[String], pet: Pet ) case class Pet( name: String, `type`: String ) // these...

It is very easy to pass information between threads using the MVar a type and its accompanying functions in Control.Concurrent: newEmptyMVar :: IO (MVar a) -- creates a new MVar a newMVar :: a -> IO (MVar a) -- creates a new MVar with the given value takeMVar :: MVar a -> IO a -- retrieve...

Summary: MVVM is an architectural pattern that is represented by three distinct components, the Model, View and ViewModel. In order to understand these three layers, it is necessary to briefly define each, followed by an explanation of how they work together. Model is the layer that drives the bus...

The BubbleSort compares each successive pair of elements in an unordered list and inverts the elements if they are not in order. The following example illustrates the bubble sort on the list {6,5,3,1,8,7,2,4} (pairs that were compared in each step are encapsulated in '**'): {6,5,3,1,8,7,2,4} {**5...

qmake is a build automation tool, which is shipped with Qt framework. It does similar job to tools such as CMake or GNU Autotools, but it is designed to be used specifically with Qt. As such it is well integrated with Qt ecosystem, notably Qt Creator IDE. If you start Qt Creator and select File -&g...

Debugging is a very powerful way to have a closer look and fix incorrectly working (or non working) code. Run code step by step First thing you need to do during debugging is to stop the code at specific locations and then run it line by line to see whether that happens what's expected. Breakp...

The JavaScript coding convention is to place the starting bracket of blocks on the same line of their declaration: if (...) { } function (a, b, ...) { } Instead of in the next line: if (...) { } function (a, b, ...) { } This has been adopted to avoid semicolon insertion ...

Since arrays are reference types, an array variable can be null. To declare a null array variable, you must declare it without a size: Dim array() As Integer Or Dim array As Integer() To check if an array is null, test to see if it Is Nothing: Dim array() As Integer If array Is Nothing Th...

If we want to replace only the first occurrence in a line, we use sed as usual: $ cat example aaaaabbbbb aaaaaccccc aaaaaddddd $ sed 's/a/x/' example xaaaabbbbb xaaaaccccc xaaaaddddd But what if we want to replace all occurrences? We just add the g pattern flag at the end: $ sed 's/a/x/...

A custom form type is a class which defines a reusable form component. Custom form components can be nested to create complicated forms. Instead of creating a form in the controller using a form builder, you can use your own type to make the code more readable, reusable and maintanable. Create a c...

manifest.json { "name": "Hello Page", "description": "Add 'Hello' to the current page.", "version": "1.0", "permissions": [ "activeTab" ], "background": { "scripts": [&quo...

To Copy Data from a CSV file to a table COPY <tablename> FROM '<filename with path>'; To insert into table user from a file named user_data.csv placed inside /home/user/: COPY user FROM '/home/user/user_data.csv'; To Copy data from pipe separated file to table COPY user FROM '/h...

To Copy table to standard o/p COPY <tablename> TO STDOUT (DELIMITER '|'); To export table user to Standard ouput: COPY user TO STDOUT (DELIMITER '|'); To Copy table to file COPY user FROM '/home/user/user_data' WITH DELIMITER '|'; To Copy the output of SQL statement to file COPY (sql st...

Data can be exported using copy command or by taking use of command line options of psql command. To Export csv data from table user to csv file: psql -p \<port> -U \<username> -d \<database> -A -F<delimiter> -c\<sql to execute> \> \<output filename with path&gt...