Tutorial by Examples: nd

Classes in MATLAB are divided into two major categories: value classes and handle classes. The major difference is that when copying an instance of a value class, the underlying data is copied to the new instance, while for handle classes the new instance points to the original data and changing val...

A simple program that writes "Hello, world!" to test.txt, reads back the data, and prints it out. Demonstrates simple file I/O operations. package main import ( "fmt" "io/ioutil" ) func main() { hello := []byte("Hello, world!") //...

package main import ( "fmt" "io/ioutil" ) func main() { files, err := ioutil.ReadDir(".") if err != nil { panic(err) } fmt.Println("Files and folders in the current directory:") for _, fileInfo := range fi...

Taking a complex JSON document in a table: CREATE TABLE mytable (data JSONB NOT NULL); CREATE INDEX mytable_idx ON mytable USING gin (data jsonb_path_ops); INSERT INTO mytable VALUES($$ { "name": "Alice", "emails": [ "[email protected]", ...

Strings in JavaScript can be enclosed in Single quotes 'hello', Double quotes "Hello" and (from ES2015, ES6) in Template Literals (backticks) `hello`. var hello = "Hello"; var world = 'world'; var helloW = `Hello World`; // ES2015 / ES6 Strings can be created...

You can require a generic type to extend multiple upper bounds. Example: we want to sort a list of numbers but Number doesn't implement Comparable. public <T extends Number & Comparable<T>> void sortNumbers( List<T> n ) { Collections.sort( n ); } In this example T must...

To keep a container running in the background, supply the -d command line option during container startup: docker run -d busybox top The option -d runs the container in detached mode. It is also equivalent to -d=true. A container in detached mode cannot be removed automatically when it stops, t...

C++17 C++17 introduces structured bindings, which makes it even easier to deal with multiple return types, as you do not need to rely upon std::tie() or do any manual tuple unpacking: std::map<std::string, int> m; // insert an element into the map and check if insertion succeeded auto [i...

While many people think that ^ means the start of a string, it actually means start of a line. For an actual start of string anchor use, \A. The string hello\nworld (or more clearly) hello world Would be matched by the regular expressions ^h, ^w and \Ah but not by \Aw

To find out the IP address of your container, use: docker inspect <container id> | grep IPAddress or use docker inspect docker inspect --format '{{ .NetworkSettings.IPAddress }}' ${CID}

Payments Table CustomerPayment_typeAmountPeterCredit100PeterCredit300JohnCredit1000JohnDebit500 select customer, sum(case when payment_type = 'credit' then amount else 0 end) as credit, sum(case when payment_type = 'debit' then amount else 0 end) as debit from payments group by ...

Unshift Use .unshift to add one or more items in the beginning of an array. For example: var array = [3, 4, 5, 6]; array.unshift(1, 2); array results in: [1, 2, 3, 4, 5, 6] Push Further .push is used to add items after the last currently existent item. For example: var array = [1, 2, 3...

var object = { key1: 10, key2: 3, key3: 40, key4: 20 }; var array = []; for(var people in object) { array.push([people, object[people]]); } Now array is [ ["key1", 10], ["key2", 3], ["key3", 40], ["key4", 20] ] ...

struct Square { private(set) var area = 0 var side: Int = 0 { didSet { area = side*side } } } public struct Square { public private(set) var area = 0 public var side: Int = 0 { didSet { area = side*side } ...

class Animal def method_missing(method, *args, &block) "Cannot call #{method} on Animal" end end => Animal.new.say_moo > "Cannot call say_moo on Animal"

Python 2.x2.6 The format() method can be used to change the alignment of the string. You have to do it with a format expression of the form :[fill_char][align_operator][width] where align_operator is one of: < forces the field to be left-aligned within width. > forces the field to be righ...

#include <stdio.h> /* for perror(), fopen(), fputs() and fclose() */ #include <stdlib.h> /* for the EXIT_* macros */ int main(int argc, char **argv) { int e = EXIT_SUCCESS; /* Get path from argument to main else default to output.txt */ char *path = (argc > 1...

To run migrations in the test environment, run this shell command: rake db:migrate RAILS_ENV=test 5.0 Starting in Rails 5.0, you can use rails instead of rake: rails db:migrate RAILS_ENV=test

To add a new indexed column email to the users table, run the command: rails generate migration AddEmailToUsers email:string:index This will generate the following migration: class AddEmailToUsers < ActiveRecord::Migration[5.0] def change add_column :users, :email, :string add_i...

c := exec.Command(name, arg...) b := &bytes.Buffer{} c.Stdout = b c.Stdin = stdin if err := c.Start(); err != nil { return nil, err } timedOut := false intTimer := time.AfterFunc(timeout, func() { log.Printf("Process taking too long. Interrupting: %s %s", name, strings...