Tutorial by Examples: l

Let's say you have a vector like so: (def my-vec [1 2 3 4 5 6]) And you want to extract the first 3 elements and get the remaining elements as a sequence. This can be done as follows: (let [[x y z & remaining] my-vec] (println "first:" x ", second:" y "third:&quot...

Swift textField.textAlignment = .Center Objective-C [textField setTextAlignment: NSTextAlignmentCenter]; In the example, we have set the NSTextAlignment to center. You can also set to .Left, .Right, .Justified and .Natural. .Natural is the default alignment for the current localization. Th...

Flask has a utility called jsonify() that makes it more convenient to return JSON responses from flask import Flask, jsonify app = Flask(__name__) @app.route('/api/get-json') def hello(): return jsonify(hello='world') # Returns HTTP Response with {"hello": "world"} ...

Python minimally evaluates Boolean expressions. >>> def true_func(): ... print("true_func()") ... return True ... >>> def false_func(): ... print("false_func()") ... return False ... >>> true_func() or false_func() true_func(...

public void iterateAndFilter() throws IOException { Path dir = Paths.get("C:/foo/bar"); PathMatcher imageFileMatcher = FileSystems.getDefault().getPathMatcher( "regex:.*(?i:jpg|jpeg|png|gif|bmp|jpe|jfif)"); try (Direc...

# For Python 2 compatibility. from __future__ import print_function import lxml.html import requests def main(): r = requests.get("https://httpbin.org") html_source = r.text root_element = lxml.html.fromstring(html_source) # Note root_element.xpath() gives a *...

Boolean(0) === false Boolean(0) will convert the number 0 into a boolean false. A shorter, but less clear, form: !!0 === false

To convert a string to boolean use Boolean(myString) or the shorter but less clear form !!myString All strings except the empty string (of length zero) are evaluated to true as booleans. Boolean('') === false // is true Boolean("") === false // is true Boolean('0') === fals...

If you have created a table with some wrong schema, then the easiest way to change the columns and their properties is change_table. Review the following example: change_table :orders do |t| t.remove :ordered_at # removes column ordered_at t.string :skew_number # adds a new column t.index...

Managed resources are resources that the runtime's garbage collector is aware and under control of. There are many classes available in the BCL, for example, such as a SqlConnection that is a wrapper class for an unmanaged resource. These classes already implement the IDisposable interface -- it's u...

It's important to let finalization ignore managed resources. The finalizer runs on another thread -- it's possible that the managed objects don't exist anymore by the time the finalizer runs. Implementing a protected Dispose(bool) method is a common practice to ensure managed resources do not have t...

Iterating over List List<String> names = new ArrayList<>(Arrays.asList("Clementine", "Duran", "Mike")); Java SE 8 names.forEach(System.out::println); If we need parallelism use names.parallelStream().forEach(System.out::println); Java SE 5 fo...

When a controller action is rendered, Rails will attempt to find a matching layout and view based on the name of the controller. Views and layouts are placed in the app/views directory. Given a request to the PeopleController#index action, Rails will search for: the layout called people in app/...

class UsersController < ApplicationController def index hashmap_or_array = [{ name: "foo", email: "[email protected]" }] respond_to do |format| format.html { render html: "Hello World" } format.json { render json: hashmap_or_array } en...

class UsersController < ApplicationController def index respond_to do |format| format.html { render html: "Hello World" } end end end This is a basic controller, with the addition of the following route (in routes.rb): resources :users, only: [:index] Will...

class UsersController < ApplicationController def index respond_to do |format| format.html do render html: "Hello #{ user_params[:name] } user_params[:sentence]" end end end private def user_params if params[:name] == "john&quo...

resources :photos do member do get 'preview' end collection do get 'dashboard' end end This creates the following routes in addition to default 7 RESTful routes: get '/photos/:id/preview', to: 'photos#preview' get '/photos/dashboards', to: '...

In JavaScript, all numbers are internally represented as floats. This means that simply using your integer as a float is all that must be done to convert it.

To convert a float to an integer, JavaScript provides multiple methods. The floor function returns the first integer less than or equal to the float. Math.floor(5.7); // 5 The ceil function returns the first integer greater than or equal to the float. Math.ceil(5.3); // 6 The round function...

#![feature(start, libc, lang_items)] #![no_std] #![no_main] // The libc crate allows importing functions from C. extern crate libc; // A list of C functions that are being imported extern { pub fn printf(format: *const u8, ...) -> i32; } #[no_mangle] // The main function, with...