Tutorial by Examples: ga

Arrays are objects, but their type is defined by the type of the contained objects. Therefore, one cannot just cast A[] to T[], but each A member of the specific A[] must be cast to a T object. Generic example: public static <T, A> T[] castArray(T[] target, A[] array) { for (int i = 0; i...

With Calendar class it is easy to find AM or PM. Calendar cal = Calendar.getInstance(); cal.setTime(new Date()); if (cal.get(Calendar.AM_PM) == Calendar.PM) System.out.println("It is PM");

To perform actions in Django using commandline or other services (where the user/request is not used), you can use the management commands. Django modules can be imported as needed. For each command a separate file needs to be created: myapp/management/commands/my_command.py (The management and...

Delegates can be used as typed function pointers: class FuncAsParameters { public void Run() { DoSomething(ErrorHandler1); DoSomething(ErrorHandler2); } public bool ErrorHandler1(string message) { Console.WriteLine(message); var shouldWeContinue = ... re...

A compound view is a custom ViewGroup that's treated as a single view by the surrounding program code. Such a ViewGroup can be really useful in DDD-like design, because it can correspond to an aggregate, in this example, a Contact. It can be reused everywhere that contact is displayed. This means t...

Let's say we have the following structure: struct MY_STRUCT { int my_int; float my_float; }; We can define MY_STRUCT to omit the struct keyword so we don't have to type struct MY_STRUCT each time we use it. This, however, is optional. typedef struct MY_STRUCT MY_STRUCT; If we th...

The .GetValueOrDefault() method returns a value even if the .HasValue property is false (unlike the Value property, which throws an exception). class Program { static void Main() { int? nullableExample = null; int result = nullableExample.GetValueOrDefault(); C...

When filtering a value that should be an integer filter_var() will return the filtered data, in this case the integer, or false if the value is not an integer. Floats are not integers: var_dump(filter_var('10', FILTER_VALIDATE_INT)); var_dump(filter_var('a10', FILTER_VALIDATE_INT)); var_dump(filt...

When validating that an integer falls in a range the check includes the minimum and maximum bounds: $options = array( 'options' => array( 'min_range' => 5, 'max_range' => 10, ) ); var_dump(filter_var('5', FILTER_VALIDATE_INT, $options)); var_dump(filter_var('...

Our randomNumbers() function can be re-written to use a generator. <?php function randomNumbers(int $length) { for ($i = 0; $i < $length; $i++) { // yield tells the PHP interpreter that this value // should be the one used in the current iteration. yield mt...

One common use case for generators is reading a file from disk and iterating over its contents. Below is a class that allows you to iterate over a CSV file. The memory usage for this script is very predictable, and will not fluctuate depending on the size of the CSV file. <?php class CsvReade...

To be able to use JDBC you need to have the JDBC driver of your database on the class path of your application. There are multiple ways to connect to a database, but the common ways are to either use the java.sql.DriverManager, or to configure and use a database specific implementation of javax.sql...

You can nest ArrayFields by passing another ArrayField as it's base_field. from django.db import models, IntegerField from django.contrib.postgres.fields import ArrayField class SudokuBoard(models.Model): numbers = ArrayField( ArrayField( models.IntegerField(), ...

Twilio's Node.JS API natively supports promises, allowing you to use promises when sending SMS messages (this example was taken and adapted directly from Twilio's API Docs). // Create an authenticated Twilio REST API client var twilio = require('twilio'); var client = new twilio.RestClient('ACCOU...

While reading content from a file is already asynchronous using the fs.readFile() method, sometimes we want to get the data in a Stream versus in a simple callback. This allows us to pipe this data to other locations or to process it as it comes in versus all at once at the end. const fs = require(...

App.xaml.cs file (App.xaml file is default, so skipped) using Xamrin.Forms namespace NavigationApp { public partial class App : Application { public static INavigation GlobalNavigation { get; private set; } public App() { InitializeComponent()...

We will model the process #Load the forecast package library(forecast) #Generate an AR1 process of length n (from Cowpertwait & Meltcalfe) # Set up variables set.seed(1234) n <- 1000 x <- matrix(0,1000,1) w <- rnorm(n) # loop to create x for (t in 2:n) x[t] <- 0.7...

Sometimes you want to do something with the exception you catch (like write to log or print a warning) and let it bubble up to the upper scope to be handled. To do so, you can rethrow any exception you catch: try { ... // some code here } catch (const SomeException& e) { std::cout &l...

You can use the filter(_:) method on SequenceType in order to create a new array containing the elements of the sequence that satisfy a given predicate, which can be provided as a closure. For example, filtering even numbers from an [Int]: let numbers = [22, 41, 23, 30] let evenNumbers = number...

This example assumes you know how to test a Flask app using pytest Below is an API that takes a JSON input with integer values a and b e.g. {"a": 1, "b": 2}, adds them up and returns sum a + b in a JSON response e.g. {"sum": 3}. # hello_add.py from flask import Flask...