Tutorial by Examples: p

&& has precedence over ||, this means that parentheses are placed to evaluate what would be evaluated together. c++ uses short-circuit evaluation in && and || to not do unnecessary executions. If the left hand side of || returns true the right hand side does not need to be evaluate...

List<Integer> immutableEmptyList = List.of(); Initializes an empty, immutable List<Integer>. List<Integer> immutableList = List.of(1, 2, 3, 4, 5); Initializes an immutable List<Integer> with five initial elements. List<Integer> mutableList = new ArrayL...

Set<Integer> immutableEmptySet = Set.of(); Initializes an empty, immutable Set<Integer>. Set<Integer> immutableSet = Set.of(1, 2, 3, 4, 5); Initializes an immutable Set<Integer> with five initial elements. Set<Integer> mutableSet = new HashSet<>(...

Map<Integer, Integer> immutableEmptyMap = Map.of(); Initializes an empty, immutable Map<Integer, Integer>. Map<Integer, Integer> immutableMap = Map.of(1, 2, 3, 4); Initializes an immutable Map<Integer, Integer> with two initial key-value entries. Map<Inte...

Service that is used for communication: import { Injectable } from '@angular/core'; import { Subject } from 'rxjs/Subject'; @Injectable() export class ComponentCommunicationService { private componentChangeSource = new Subject(); private newDateCreationSource = new Subject<Date&...

Model: public class User { public int ID { get; set; } public string FirstName { get; set; } public DateTime DateOfBirth { get; set; } } If we want to display the users in different Views, it would be better to create a standardized layout for these users wherever they need...

Factory pattern decouples object creation and allows creation by name using a common interface: class Animal{ public: virtual std::shared_ptr<Animal> clone() const = 0; virtual std::string getname() const = 0; }; class Bear: public Animal{ public: virtual std::shared_ptr...

Display Templates can be used to standardize the layout of an object, so let's now see how we can do the same thing for these objects when editing them. Just like display templates, there's two ways to call editor templates for a given type: Html.EditorFor() Html.EditorForModel() Editor templat...

#include <mutex> #include <condition_variable> class Semaphore { public: Semaphore (int count_ = 0) : count(count_) { } inline void notify( int tid ) { std::unique_lock<std::mutex> lock(mtx); count++; cout <...

The following function adds four threads. Three threads compete for the semaphore, which is set to a count of one. A slower thread calls notify_one(), allowing one of the waiting threads to proceed. The result is that s1 immediately starts spinning, causing the Semaphore's usage count to remain be...

Introduction Julia uses the following syntax for dictionaries: Dict({k₁ => v₁, k₂ => v₂, …, kₙ₋₁ => vₙ₋₁, kₙ => vₙ) While Python and JSON looks like this: {k₁: v₁, k₂: v₂, …, kₙ₋₁: vₙ₋₁, kₙ: vₙ} For illustrative purposes we could also use this syntax in Julia and add new seman...

For loops can be really useful in TWIG, allowing the creation of data-dynamic web pages. Say we create a simple array of numbers: {% set array = "3,1,2" %} We can then iterate over the array and print out whatever we want. Any data within the array block will be outputted in relation ...

Coercion happens with data types in R, often implicitly, so that the data can accommodate all the values. For example, x = 1:3 x [1] 1 2 3 typeof(x) #[1] "integer" x[2] = "hi" x #[1] "1" "hi" "3" typeof(x) #[1] "character" ...

The Builder Pattern decouples the creation of the object from the object itself. The main idea behind is that an object does not have to be responsible for its own creation. The correct and valid assembly of a complex object may be a complicated task in itself, so this task can be delegated to anoth...

Renaming the server.php to index.php Copy the .htaccess from public folder to root folder Changing .htaccess a bit as follows for statics: RewriteEngine On RewriteCond %{REQUEST_FILENAME} !-d RewriteRule ^(.*)/$ /$1 [L,R=301] RewriteCond %{REQUEST_URI} !(\.css|\.js|\.png|\.jpg|\.gif|ro...

Kernel manages operating system resources. User program can only access to those resources by making system calls to the kernel. System call is similar to an API of kernel, which in term, runs kernel tasks your program needs. str = "something" // run on user space x = x + 1 // run on use...

Use top command to exam CPU time allocation between user space and kernel space. Explanation: 24.8 us (user space): 24.8% of CPU time is spent on user process. 0.5 sy (system): 0.5% of CPU time is spent on kernel space. ni (niceness): the ratio of CPU time spent on low priority processes. i...

Use time command. time ./perl-timeout-example 100.100.100 We could not ping the desired address! real 0m5.0013s user 0m0.004s sys 0m0.008s Real: Total time from start to finish of the call, including the CPU time spent on other processes. User: The amount of CPU time spent i...

Steps to copy heroku database to local database: 1. Run copy process in terminal: heroku pg:pull DATABASE_URL change_to_your_data_base_name --app change_to_your_app_name 2. Change db owner using this query: GRANT ALL PRIVILEGES ON DATABASE change_to_your_data_base_name to change_to_your_user; A...

We also need to set correct permissions for storage files in the server. So, we need to give a write permission in the storage directory as follows: $ chmod -R 777 ./storage ./bootstrap or you may use $ sudo chmod -R 777 ./storage ./bootstrap For windows Make sure you are an admin user on t...