Tutorial by Examples: i

String concatenation is when you combine two or more strings into a single string variable. String concatenation is performed with the & symbol. Dim one As String = "Hello " Dim two As String = "there" Dim result As String = one & two Non-string values will be conv...

7.0 OrElse Sub Main() Dim elements As List(Of Integer) = Nothing Dim average As Double = AverageElementsOrElse(elements) Console.WriteLine(average) ' Writes 0 to Console Try 'Throws ArgumentNullException average = AverageElementsOr(elements) Catch ex ...

Joseph Fourier showed that any periodic wave can be represented by a sum of simple sine waves. This sum is called the Fourier Series. The Fourier Series only holds while the system is linear. If there is, eg, some overflow effect (a threshold where the output remains the same no matter how much inpu...

using System; using System.Threading; using System.Threading.Tasks; class Program { static void Main( string[] args ) { object sync = new object(); int sum = 0; Parallel.For( 1, 1000, ( i ) => { lock( sync ) sum = sum + i; // lock is necessa...

Using the Library Database, we try to find the last book added to the database for each author. For this simple example we assume an always incrementing Id for each record added. SELECT MostRecentBook.Name, MostRecentBook.Title FROM ( SELECT Authors.Name, Books.Title, ...

As of Qt 5.1 and later you can use QQmlApplicationEngine instead of QQuickView to load and render a QML script. With QQmlApplicationEngine you do need to use a QML Window type as your root element. You can obtain the root context from the engine where you can then add global properties to the cont...

Not all objects can be converted to a JSON string. When an object has cyclic self-references, the conversion will fail. This is typically the case for hierarchical data structures where parent and child both reference each other: const world = { name: 'World', regions: [] }; world.region...

Creating a ServiceHost programmatically (without config file) in its most basic form: namespace ConsoleHost { class ConsoleHost { ServiceHost mHost; public Console() { mHost = new ServiceHost(typeof(Example), new Uri("net.tcp://localhost:9000/Example")); ...

class ClassWithAReallyLongName { public: class Iterator { /* ... */ }; Iterator end(); }; Defining the member end with a trailing return type: auto ClassWithAReallyLongName::end() -> Iterator { return Iterator(); } Defining the member end without a trailing return type: Clas...

>>> df ID Year Jan_salary Feb_salary Mar_salary 0 1 2016 4500 4200 4700 1 2 2016 3800 3600 4400 2 3 2016 5500 5200 5300 >>> melted_df = pd.melt(df,id_vars=['ID','Year'], v...

Example for searching just one user with a specific id, you should do: $options = ['limit' => 1]; $filter = ['_id' => new \MongoDB\BSON\ObjectID('578ff7c3648c940e008b457a')]; $query = new \MongoDB\Driver\Query($filter, $options); $cursor = $manager->executeQuery('database_name.collect...

Example for searching multiple users with the name "Mike": $filter = ['name' => 'Mike']; $query = new \MongoDB\Driver\Query($filter); $cursor = $manager->executeQuery('database_name.collection_name', $query); foreach ($cursor as $doc) { var_dump($doc); }

Example for adding a document: $document = [ 'name' => 'John', 'active' => true, 'info' => ['genre' => 'male', 'age' => 30] ]; $bulk = new \MongoDB\Driver\BulkWrite; $_id1 = $bulk->insert($document); $result = $manager->executeBulkWrite('database_name.collect...

Navigation Drawers are used to navigate to top-level destinations in an app. Make sure that you have added design support library in your build.gradle file under dependencies: dependencies { // ... compile 'com.android.support:design:25.3.1' } Next, add the DrawerLayout and Navigati...

Comments are used to explain code when the basic code itself isn't clear. Python ignores comments, and so will not execute code in there, or raise syntax errors for plain english sentences. Single-line comments begin with the hash character (#) and are terminated by the end of line. Single lin...

auto can also cause problems where expression templates come into play: auto mult(int c) { return c * std::valarray<int>{1}; } auto v = mult(3); std::cout << v[0]; // some value that could be, but almost certainly is not, 3. The reason is that operator* on valarray gives yo...

Transact-SQL supports two forms of comment writing. Comments are ignored by the database engine, and are meant for people to read. Comments are preceded by -- and are ignored until a new line is encountered: -- This is a comment SELECT * FROM MyTable -- This is another comment WHERE Id = 1; ...

Given a local directory with the following contents: └── dir1 ├── subdir1 └── subdir2 We want to create the same subdir1, subdir2 under a new directory dir2, which does not exist yet. import os os.makedirs("./dir2/subdir1") os.makedirs("./dir2/subdir2") R...

select * from sys.dm_resource_governor_workload_groups select * from sys.dm_resource_governor_resource_pools

First create a resource pool besides the default one CREATE RESOURCE POOL [PoolAdhoc] WITH(min_cpu_percent=0, max_cpu_percent=50, min_memory_percent=0, max_memory_percent=50) GO Create the worload group for the pool CREATE WORKLOAD GROUP [AdhocMedium] WITH(importa...