Tutorial by Examples: nd

To begin, install Node.js on your development computer. Windows: Navigate to the download page and download/run the installer. Mac: Navigate to the download page and download/run the installer. Alternatively, you can install Node via Homebrew using brew install node. Homebrew is a command-line pac...

A very common guideline in object oriented design is "as little as possible but as much as necessary". This also applies to the strategy pattern: It is usually advisable to hide implementation details, for example which classes actually implement strategies. For simple strategies which do...

CASE's shorthand variant evaluates an expression (usually a column) against a series of values. This variant is a bit shorter, and saves repeating the evaluated expression over and over again. The ELSE clause can still be used, though: SELECT Id, ItemId, Price, CASE Price WHEN 5 THEN 'CHEAP' ...

When calling a function without an explicit namespace qualifier, the compiler can choose to call a function within a namespace if one of the parameter types to that function is also in that namespace. This is called "Argument Dependent Lookup", or ADL: namespace Test { int call(int i)...

void Main() { unsafe { int[] a = {1, 2, 3}; fixed(int* b = a) { Console.WriteLine(b[4]); } } } Running this code creates an array of length 3, but then tries to get the 5th item (index 4). On my machine, this printed 1910457872, bu...

This example uses the Dropbox .NET library to try to get the metadata for an item at a particular path, and checks for a NotFound error: try { var metadata = await this.client.Files.GetMetadataAsync("/non-existant path"); Console.WriteLine(metadata.Name); } catch (Dropbox.Api.A...

> mysqldump -u username -p [other options] Enter password: If you need to specify the password on the command line (e.g. in a script), you can add it after the -p option without a space: > mysqldump -u username -ppassword [other options] If you password contains spaces or special chara...

In this tutorial we're going to learn how to set up the PayPal Android SDK to process a simple payment via either a PayPal payment or a credit card purchase. At the end of this example, you should have a simple button in an application that, when clicked, will forward the user to PayPal to confirm a...

If you need to get data from a JSONObject, consider the following example: String json = "{\"foo\":\"bar\",\"temperature\":21.5,\"year\":2016,\"message\":{\"Hello\":\"world\"},\"months\":[\"January\",\&qu...

When an API is marked with NS_REFINED_FOR_SWIFT, it will be prefixed with two underscores (__) when imported to Swift: @interface MyClass : NSObject - (NSInteger)indexOfObject:(id)obj NS_REFINED_FOR_SWIFT; @end The generated interface looks like this: public class MyClass : NSObject { publ...

This uses the Dropbox Python SDK to create a shared link for a file and also supplies a requested visibility and expiration in the settings: import datetime import dropbox dbx = dropbox.Dropbox("<ACCESS_TOKEN>") expires = datetime.datetime.now() + datetime.timedelta(days=30...

#include <stdio.h> #include <string.h> int main(void) { /* Always ensure that your string is large enough to contain the characters * and a terminating NUL character ('\0')! */ char mystring[10]; /* Copy "foo" into `mystring`, until a NUL character is en...

int* foo(int bar) { int baz = 6; baz += bar; return &baz; /* (&baz) copied to new memory location outside of foo. */ } /* (1) The lifetime of baz and bar end here as they have automatic storage * duration (local variables), thus the returned pointer is not valid! */ ...

Starting with a given list a: a = [1, 2, 3, 4, 5] append(value) – appends a new element to the end of the list. # Append values 6, 7, and 7 to the list a.append(6) a.append(7) a.append(7) # a: [1, 2, 3, 4, 5, 6, 7, 7] # Append another list b = [8, 9] a.append(b) # a: [1, 2, 3, 4, ...

Note: The width and height attributes are not deprecated on images and never have been. Their use has been made much stricter though. The dimensions of an image can be specified using the width and height attributes of the image tag: <img src="images/200x200-img.png" width="2...

Syntax for accessing rows and columns: [, [[, and $ This topic covers the most common syntax to access specific rows and columns of a data frame. These are Like a matrix with single brackets data[rows, columns] Using row and column numbers Using column (and row) names Like a list: Wi...

$( "#accordion" ).accordion( "destroy" ); This will remove the accordion functionality completely and show default HTML removing all the jQuery-UI elements. This method does not take any arguments.

$( "#accordion" ).accordion( "disable" ); This method will disable the accordion, i.e. the headers are not selectable making the content read only and static. This method does not take any arguments.

A typical email has three main components: A recipient (represented as an email address) A subject A message body Sending mail in PHP can be as simple as calling the built-in function mail(). mail() takes up to five parameters but the first three are all that is required to send an email (al...

MATLAB allows for several methods to index (access) elements of matrices and arrays: Subscript indexing - where you specify the position of the elements you want in each dimension of the matrix separately. Linear indexing - where the matrix is treated as a vector, no matter its dimensions. That ...