Tutorial by Examples: i

In most cases, it is illegal to access an object of one type as though it were a different type (disregarding cv-qualifiers). Example: float x = 42; int y = reinterpret_cast<int&>(x); The result is undefined behavior. There are some exceptions to this strict aliasing rule: An obj...

Consider writing a "hello world!" program in c. Lets say our source code is in a file called source.c, now in order to run our program we need to compile it, typically on Linux (using gcc) we would need to type $> gcc source.c -o output where output is the name of the executable to be g...

This example will call the windows calculator. It's important to notice that the exit code will vary accordingly to the program/script that is being called. package process.example; import java.io.IOException; public class App { public static void main(String[] args) { try { ...

The ProcessBuilder class makes it easy to send a command through the command line. All it requires is a List of Strings that make up the commands to be entered. You simply call the start() method on your ProcessBuilder instance to execute the command. If you have a program called Add.exe which take...

In general when making a call to the command line, the program will send the command and then continue its execution. However you may want to wait for the called program to finish before continuing your own execution (ex. The called program will write data to a file and your program needs that to a...

This proxy simply appends the string " went through proxy" to every string property set on the target object. let object = {}; let handler = { set(target, prop, value){ // Note that ES6 object syntax is used if('string' === typeof value){ target[prop] = valu...

Laravel's events allows to implement the Observer pattern. This can be used to send a welcome email to a user whenever they register on your application. New events and listeners can be generated using the artisan command line utility after registering the event and their particular listener in App...

Get current time: Time.now Time.new # is equivalent if used with no parameters Get specific time: Time.new(2010, 3, 10) #10 March 2010 (Midnight) Time.new(2015, 5, 3, 10, 14) #10:14 AM on 3 May 2015 Time.new(2050, "May", 3, 21, 8, 16, "+10:00") #09:08:16 PM on 3 May 2050...

DATA: <TABLE NAME> TYPE <SORTED|STANDARD|HASHED> TABLE OF <TYPE NAME> WITH <UNIQUE|NON-UNIQUE> KEY <FIELDS FOR KEY>. Standard Table This table has all of the entries stored in a linear fashion and records are accessed in a linear way. For large table sizes, ...

Notice, this is only for angular-cli up to 1.0.0-beta.10 version ! Some libraries or plugins may not have typings. Without these, TypeScript can't type check them and therefore causes compilation errors. These libraries can still be used but differently than imported modules. Include a scr...

For example: ActiveRecord::Base.transaction do david.withdrawal(100) mary.deposit(100) end This example will only take money from David and give it to Mary if neither withdrawal nor deposit raise an exception. Exceptions will force a ROLLBACK that returns the database to the state before ...

Though the transaction class method is called on some ActiveRecord class, the objects within the transaction block need not all be instances of that class. This is because transactions are per-database connection, not per-model. In this example a balance record is transactionally saved even though ...

A transaction acts on a single database connection. If you have multiple class-specific databases, the transaction will not protect interaction among them. One workaround is to begin a transaction on each class whose models you alter: Student.transaction do Course.transaction do course.enro...

Both #save and #destroy come wrapped in a transaction that ensures that whatever you do in validations or callbacks will happen under its protected cover. So you can use validations to check for values that the transaction depends on or you can raise exceptions in the callbacks to rollback, includin...

ActiveRecord::Base.transaction uses the ActiveRecord::Rollback exception to distinguish a deliberate rollback from other exceptional situations. Normally, raising an exception will cause the .transaction method to rollback the database transaction and pass on the exception. But if you raise an Activ...

Shade is a library developed by OpenStack to simplify interactions with OpenStack clouds, like DreamHost. $ pip install shade

Create a file named launch-server.yaml, that will be our playbook. The first part of the playbook is a list of hosts that your playbook will run on, we only have one, localhost. - hosts: localhost Then we need to define a list of tasks to perform in this playbook. We will only have one that lau...

Run the Ansible playbook: $ ansible-playbook launch-server.yaml You should see output like PLAY [localhost] *************************************************************** TASK [setup] ******************************************************************* ok: [localhost] TASK [launch an U...

Using NuGet Install-Package Cirrious.FluentLayout An expanded example based on the starter example at the GitHub Page, a simple first name, last name labels and fields all stacked one on top of the other: public override void ViewDidLoad() { //create our labels and fields var firstNa...

Built-in functionals: lapply(), sapply(), and mapply() R comes with built-in functionals, of which perhaps the most well-known are the apply family of functions. Here is a description of some of the most common apply functions: lapply() = takes a list as an argument and applies the specified ...