Tutorial by Examples: ha

Examples below are given in Ruby, but same matchers should be available in any modern language. Let’s say we have the string "AℵNaïve", produced by Messy Artificial Intelligence. It consists of letters, but generic \w matcher won’t match much: ▶ "AℵNaïve"[/\w+/] #⇒ "A&q...

In this example we have an existing table, SuperHeros. This table contains a primary key ID. We will add a new table in order to store the powers of each super hero: CREATE TABLE HeroPowers ( ID int NOT NULL PRIMARY KEY, Name nvarchar(MAX) NOT NULL, HeroId int REFERENCES SuperHero...

The strchr and strrchr functions find a character in a string, that is in a NUL-terminated character array. strchr return a pointer to the first occurrence and strrchr to the last one. #include <stdio.h> #include <stdlib.h> #include <string.h> int main(void) { char toSe...

countMatches method from org.apache.commons.lang3.StringUtils is typically used to count occurences of a substring or character in a String: import org.apache.commons.lang3.StringUtils; String text = "One fish, two fish, red fish, blue fish"; // count occurrences of a substring Str...

Hashes can be understood as lookup-tables. You can access its contents by specifiying a key for each of them. Keys must be strings. If they're not, they will be converted to strings. If you give the hash simply a known key, it will serve you its value. # Elements are in (key, value, key, value) se...

HTML <p>My shadow always follows me.</p> CSS p { -webkit-filter: drop-shadow(10px 10px 1px green); filter: drop-shadow(10px 10px 1px green); } Result

Generally you should avoid using the default database role (often postgres) in your application. You should instead create a user with lower levels of privileges. Here we make one called niceusername and give it a password very-strong-password CREATE ROLE niceusername with PASSWORD 'very-strong-pas...

hash( (1, 2) ) # ok hash( ([], {"hello"}) # not ok, since lists and sets are not hashabe Thus a tuple can be put inside a set or as a key in a dict only if each of its elements can. { (1, 2) } # ok { ([], {"hello"}) ) # not ok

Many developers like to customize the font, text, and background color of their IDE's. You can do this in Xcode by opening the app preference pane, either by going to XCODE->Preferences, or by pressing '⌘,' With the preference pane open you can click on the 'Fonts and Colors' tab. From her...

The Switch statement works very well with Enum values enum CarModel { case Standard, Fast, VeryFast } let car = CarModel.Standard switch car { case .Standard: print("Standard") case .Fast: print("Fast") case .VeryFast: print("VeryFast") } Since we ...

Ansible can be installed on CentOS or other Red Hat based systems. Firstly you should install the prerequisites: sudo yum -y update sudo yum -y install gcc libffi-devel openssl-devel python-pip python-devel then install Ansible with pip: sudo pip install ansible I can recommend for you to u...

Match any: Must match at least one string. In this example the product type must be either 'electronics', 'books', or 'video'. SELECT * FROM purchase_table WHERE product_type LIKE ANY ('electronics', 'books', 'video'); Match all (must meet all requirements). In this example both 'united...

Once the instance of the BackgroundWorker has been declared, it must be given properties and event handlers for the tasks it performs. /* This is the backgroundworker's "DoWork" event handler. This method is what will contain all the work you wish to have your progra...

Python supports a translate method on the str type which allows you to specify the translation table (used for replacements) as well as any characters which should be deleted in the process. str.translate(table[, deletechars]) ParameterDescriptiontableIt is a lookup table that defines the mappin...

Properties can be added with categories using associated objects, a feature of the Objective-C runtime. Note that the property declaration of retain, nonatomic matches the last argument to objc_setAssociatedObject. See Attach object to another existing object for explanations. #import <objc/run...

As Handlers are used to send Messages and Runnables to a Thread's message queue it's easy to implement event based communication between multiple Threads. Every Thread that has a Looper is able to receive and process messages. A HandlerThread is a Thread that implements such a Looper, for example th...

g$ The above matches one letter (the letter g) at the end of a string in most regex engines (not in Oniguruma, where the $ anchor matches the end of a line by default, and the m (MULTILINE) modifier is used to make a . match any characters including line break characters, as a DOTALL modifier in ...

A Hash includes the Enumerable module, which provides several iteration methods, such as: Enumerable#each, Enumerable#each_pair, Enumerable#each_key, and Enumerable#each_value. .each and .each_pair iterate over each key-value pair: h = { "first_name" => "John", "last_na...

C# has several operators that can be combined with an = sign to evaluate the result of the operator and then assign the result to the original variable. Example: x += y is the same as x = x + y Assignment operators: += -= *= /= %= &= |= ^= <<= >>=

In the HTTP server code (e.g. server.js): const EventEmitter = require('events') const serverEvents = new EventEmitter() // Set up an HTTP server const http = require('http') const httpServer = http.createServer((request, response) => { // Handler the request... // Then emit an event...