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The static (compile-time) type is used rather than the dynamic (run-time type) to match parameters. public class Base { public virtual string GetName() { return "Base"; } } public class Derived : Base { public override string GetName() { ...

What is Ubuntu Ubuntu is an open source software platform, but colloquially, when Ubuntu is referred to it's mainly toward the Ubuntu operating system. Ubuntu is based on Debian and uses the same package management system (deb and apt). Installation So you want to give Ubuntu a try! That's gr...

You may need to convert a Stream emitting Optional to a Stream of values, emitting only values from existing Optional. (ie: without null value and not dealing with Optional.empty()). Optional<String> op1 = Optional.empty(); Optional<String> op2 = Optional.of("Hello World");...

The function php_sapi_name() and the constant PHP_SAPI both return the type of interface (Server API) that is being used by PHP. They can be used to restrict the execution of a script to the command line, by checking whether the output of the function is equal to cli. if (php_sapi_name() === 'cli')...

Add/remove fields in existing tables Create a migration by running: rails generate migration AddTitleToCategories title:string This will create a migration that adds a title column to a categories table: class AddTitleToCategories < ActiveRecord::Migration[5.0] def change add_column...

preg_match checks whether a string matches the regular expression. $string = 'This is a string which contains numbers: 12345'; $isMatched = preg_match('%^[a-zA-Z]+: [0-9]+$%', $string); var_dump($isMatched); // bool(true) If you pass in a third parameter, it will be populated with the matchi...

This is the Python 2 syntax, note the commas , on the raise and except lines: Python 2.x2.3 try: raise IOError, "input/output error" except IOError, exc: print exc In Python 3, the , syntax is dropped and replaced by parenthesis and the as keyword: try: raise IOErro...

"string".upcase # => "STRING" "STRING".downcase # => "string" "String".swapcase # => "sTRING" "string".capitalize # => "String" These four methods do not modify the original receiver. For exampl...

interface IFoo { } class Foo : IFoo { } class Bar : IFoo { } var item0 = new Foo(); var item1 = new Foo(); var item2 = new Bar(); var item3 = new Bar(); var collection = new IFoo[] { item0, item1, item2, item3 }; Using OfType var foos = collection.OfType<Foo>(); // result: IEnum...

To develop an application for iOS, you should start with an application called Xcode. There are other alternative tools you can use, but Xcode is Apple's official tool. Note, however, that it only runs on macOS. The latest official version is Xcode 8.3.3 with Xcode 9 (currently in beta) due to be re...

As of Tensorflow version 1.0 installation has become much easier to perform. At minimum to install TensorFlow one needs pip installed on their machine with a python version of at least 2.7 or 3.3+. pip install --upgrade tensorflow # for Python 2.7 pip3 install --upgrade tensorflow # for ...

There are two ways to connect to a MySQL/MariaDB server, depending on your infrastructure. Standard (TCP/IP) connection $dsn = 'mysql:dbname=demo;host=server;port=3306;charset=utf8'; $connection = new \PDO($dsn, $username, $password); // throw exceptions, when SQL error is caused $connection-...

Detailed instructions on getting google-maps set up or installed.

Eloquent is the ORM built into the Laravel framework. It allows you to interact with your database tables in an object-oriented manner, by use of the ActiveRecord pattern. A single model class usually maps to a single database table, and also relationships of different types (one-to-one, one-to-man...

INSERT INTO `table_name` (`index_field`, `other_field_1`, `other_field_2`) VALUES ('index_value', 'insert_value', 'other_value') ON DUPLICATE KEY UPDATE `other_field_1` = 'update_value', `other_field_2` = VALUES(`other_field_2`); This will INSERT into ta...

Merges two collections to create a distinct collection using the default equality comparer int[] numbers1 = { 1, 2, 3 }; int[] numbers2 = { 2, 3, 4, 5 }; var allElement = numbers1.Union(numbers2); // AllElement now contains 1,2,3,4,5 Live Demo on .NET Fiddle

virtualenv is a tool to build isolated Python environments. This program creates a folder which contains all the necessary executables to use the packages that a Python project would need. Installing the virtualenv tool This is only required once. The virtualenv program may be available through yo...

Normally you would want to avoid using cursors as they can have negative impacts on performance. However in some special cases you may need to loop through your data record by record and perform some action. DECLARE @orderId AS INT -- here we are creating our cursor, as a local cursor and only a...

A module is a file containing Python definitions and statements. Function is a piece of code which execute some logic. >>> pow(2,3) #8 To check the built in function in python we can use dir(). If called without an argument, return the names in the current scope. Else, return an alph...

If you've got a session which you wish to destroy, you can do this with session_destroy() /* Let us assume that our session looks like this: Array([firstname] => Jon, [id] => 123) We first need to start our session: */ session_start(); /* We can now remove all the v...