Tutorial by Examples: in

The 'javac' command - getting started

Simple example Assuming that the "HelloWorld.java" contains the following Java source: public class HelloWorld { public static void main(String[] args) { System.out.println("Hello world!"); } } (For an explanation of the above code, please refer to Gettin...

Java Language • Java Compiler - 'javac'

Intervals

Standard You don't need to create the variable, but it's a good practice as you can use that variable with clearInterval to stop the currently running interval. var int = setInterval("doSomething()", 5000 ); /* 5 seconds */ var int = setInterval(doSomething, 5000 ); /* same thing, no qu...

JavaScript • Intervals and Timeouts

Cut (remove choice points)

Sometimes it is desirable to prevent Prolog from backtracking into alternative solutions. The basic tool available to the programmer to stop prolog from continuing futher in its backtrack is the cut operator. consider the following. % (percent signs mean comments) % a is the parent of b, c, and d....

Prolog Language • Control structures

Definition

Official page: https://www.rebar3.org/ Source code: https://github.com/erlang/rebar3 Rebar3 is mainly a dependency manager for Erlang and Elixir projects, but it also offers several other features, like bootstrapping projects (according to several templates, following the OTP principles), task exe...

Erlang Language • Rebar3

Installing Rebar3

Rebar3 is written in Erlang, so you need Erlang to run it. It is available as a binary that you can download and run. Just fetch the nightly build and give it execution permissions: $ wget https://s3.amazonaws.com/rebar3/rebar3 && chmod +x rebar3 Place this binary in a convenient place a...

Erlang Language • Rebar3

Installing from Source Code

As Rebar3 is free, open source and written in Erlang, it's possible to simply clone and build it from the source code. $ git clone https://github.com/erlang/rebar3.git $ cd rebar3 $ ./bootstrap This will create the rebar3 script, which you can put on your PATH or link to /usr/local/bin as expl...

Erlang Language • Rebar3

Bootstrapping a new Erlang project

To bootstrap a new Erlang project, simply choose the template you want to use from the list. The available templates can be retrieved by the following command: $ rebar3 new app (built-in): Complete OTP Application structure cmake (built-in): Standalone Makefile for building C/C++ in c_src escr...

Erlang Language • Rebar3

ListView in AlertDialog

We can always use ListView or RecyclerView for selection from list of items, but if we have small amount of choices and among those choices we want user to select one, we can use AlertDialog.Builder setAdapter. private void showDialog() { AlertDialog.Builder builder = new AlertDia...

Android • Dialog

Creating a hash table

Hash tables are created by make-hash-table: (defvar *my-table* (make-hash-table)) The function may take keyword parameters to further specify the behavior of the resulting hash table: test: Selects the function used to compare keys for equality. Maybe a designator for one of the functions eq,...

common-lisp • Hash tables

Iterating over the entries of a hash table with maphash

(defun print-entry (key value) (format t "~A => ~A~%" key value)) (maphash #'print-entry *my-table*) ;; => NIL Using maphash allows to iterate over the entries of a hash table. The order of iteration is unspecified. The first argument is a function accepting two parameters: ...

common-lisp • Hash tables

Using Single Slots

Single slots are used when a child component only defines one slot within its template. The page component above uses a single slot to distribute content. An example of the page component's template using a single slot is below: <html> <head> <title>Page Title</t...

Vue.js • Slots

Using Named Slots

Named slots work similarly to single slots but instead allow you to distribute content to different regions within your child component template. Take the page component from the previous example but modify it's template so it is as follows: <html> <head> <title>Pag...

Vue.js • Slots

Deploying your application

Make sure you are in the directory that contains your Rails app, then create an app on Heroku. $ heroku create example Creating ⬢ example... done https://example.herokuapp.com/ | https://git.heroku.com/example.git The first URL of the ouput, http://example.herokuapp.com, is the location the ap...

Ruby on Rails • Deploying a Rails app on Heroku

Check matching fields in two files

Given these two CSV files: $ cat file1 1,line1 2,line2 3,line3 4,line4 $ cat file2 1,line3 2,line4 3,line5 4,line6 To print those lines in file2 whose second column occurs also in the first file we can say: $ awk -F, 'FNR==NR {lines[$2]; next} $2 in lines' file1 file2 1,line3 2,line4...

awk • Two-file processing

Checking the syntax of a script with "-n"

The -n flag enables you to check the syntax of a script without having to execute it: ~> $ bash -n testscript.sh testscript.sh: line 128: unexpected EOF while looking for matching `"' testscript.sh: line 130: syntax error: unexpected end of file

Bash • Debugging

Installation or Setup

Download and install the WiX Toolset from wixtoolset.org. The installer for the WiX Toolset provides also the integration with Visual Studio, after the installation you should be able to create WiX specific projects. Warnings Admin rights are needed. Some versions of WiX are compatible only with...

wix • Getting started with wix

Installation or Setup

Detailed instructions on getting asp.net-identity set up or installed.

asp.net-identity • Getting started with asp.net-identity

Split routes into multiple files

If your routes file is overwhelmingly big, you can put your routes in multiple files and include each of the files with Ruby’s require_relative method: config/routes.rb: YourAppName::Application.routes.draw do require_relative 'routes/admin_routes' require_relative 'routes/sidekiq_routes' ...

Ruby on Rails • Routing

Ignoring return values of library functions

Almost every function in C standard library returns something on success, and something else on error. For example, malloc will return a pointer to the memory block allocated by the function on success, and, if the function failed to allocate the requested block of memory, a null pointer. So you sho...

C Language • Common pitfalls

Installation or Setup

On Windows Download the Visual Studio Code installer for Windows. Once it is downloaded, run the installer (VSCodeSetup-version.exe). This will only take a minute. By default, VS Code is installed under C:\Program Files (x86)\Microsoft VS Code for a 64-bit machine. Note: .NET Framework 4.5.2...

vscode • Getting started with vscode