Tutorial by Examples: e

Sometimes it may be required to find out which directory consuming how much disk space especially when you are used df -h and realized your available disk space is low. du: du command summarizes disk usage of the set of FILEs, recursively for directories. It's often uses with -sh option: -s, --s...

First, ensure you have installed mongodb and express via npm. Then, in a file conventionally titled db.js, use the following code: var MongoClient = require('mongodb').MongoClient var state = { db: null, } exports.connect = function(url, done) { if (state.db) return done() M...

The following example is high level coverage of the key concepts and basic skeletal setup:- Collects credentials from the user (Usually from a login screen you've created) Authenticates the credentials with the server (stores custom authentication) Stores the credentials on the device Exte...

A frequent reason why your read operation may not work is because your security rules reject the operation, for example because you're not authenticated (by default a database can only be accessed by an authenticated user). You can see these security rule violations in the JavaScript console of you...

Add a -behaviour directive to your module to indicate that it follows a behaviour: -behaviour(gen_server). The American spelling is also accepted: -behavior(gen_server). Now the compiler will give a warning if you've forgotten to implement and export any of the functions required by the beha...

You can define your own behaviour by adding -callback directives in your module. For example, if modules implementing your behaviour need to have a foo function that takes an integer and returns an atom: -module(my_behaviour). -callback foo(integer()) -> atom(). If you use this behaviour in...

It's easiest to show a binary search on numbers using pseudo-code int array[1000] = { sorted list of numbers }; int N = 100; // number of entries in search space; int high, low, mid; // our temporaries int x; // value to search for low = 0; high = N -1; while(low < high) { mid = (...

In this iText 5 example, we'll create a text field and we'll add it to a PDF: public void manipulatePdf(String src, String dest) throws DocumentException, IOException { PdfReader reader = new PdfReader(src); PdfStamper stamper = new PdfStamper(reader, new FileOutputStream(dest)); T...

In this iText 7 example, we'll create a text field and we'll add it to a PDF: public void manipulatePdf(String src, String dest) throws IOException { PdfReader reader = new PdfReader(src); PdfDocument pdf = new PdfDocument(reader, new PdfWriter(dest)); PdfAcroForm form = PdfAcroFor...

In this iText 5 example, we'll change the properties and the value of a text field: public void manipulatePdf(String src, String dest) throws DocumentException, IOException { PdfReader reader = new PdfReader(src); PdfStamper stamper = new PdfStamper(reader, new FileOutputStream(dest)); ...

In this iText 7 example, we'll change the properties and the value of a text field: public void manipulatePdf(String src, String dest) throws IOException { PdfReader reader = new PdfReader(src); PdfDocument pdf = new PdfDocument(reader, new PdfWriter(dest)); PdfAcroForm form = PdfA...

To show you how work the views, we will assume that we want to query the document of type people. To do so, we will first need a design document that will hold our views. Note: for the purpose of the example, we will use many views inside of 1 design document. Therefore, in a production environment...

Integer Basics Standard ML of New Jersey v110.78 [built: Thu Jul 23 11:21:58 2015] - 6; val it = 6 : int - ~6; val it = ~6 : int - 6 + ~6; val it = 0 : int Integer Division - 6 div 3; val it = 2 : int - 6 div 4; val it = 0 : int - 3 div 6; val it = 0 : int Integer Value Bounds Us...

Real Number Basics - 6.0; val it = 6.0 : real - ~6.0; val it = ~6.0 : real - 6.0 + ~6.0; val it = 0.0 : real - 6.0 / 3.0; val it = 2.0 : real - 4.0 / 6.0; val it = 0.666666666667 : real Real Value Bounds Using Real Basis Library Functions - Real.maxFinite; val it = 1.79769313486E308 ...

Rounding Values midway between two integers go toward the nearest even value. - round(4.5); val it = 4 : int - round(3.5); val it = 4 : int Truncation val it = 4 : int - trunc(4.5); val it = 4 : int - trunc(3.5); val it = 3 : int Floor and Ceiling - ceil(4.5); val it = 5 : int - f...

Cannot add Integer and Real* - 5 + 1.0; stdIn:1.2-10.4 Error: operator and operand don't agree [overload conflict] operator domain: [+ ty] * [+ ty] operand: [+ ty] * real in expression: 5 + 1.0

- real(6); val it = 6.0 : real

Instead of running intensive tasks into JavaFX Thread that should be done into a Service.So what basically is a Service? A Service is a class which is creating a new Thread every time you are starting it and is passing a Task to it to do some work.The Service can return or not a value. Below is ...

Standard ML doesn't have built-in support for lazy evaluation. Some implementations, notably SML/NJ, have nonstandard lazy evaluation primitives, but programs that use those primitives won't be portable. Lazy suspensions can also be implemented in a portable manner, using Standard ML's module system...

JavaFX has a binding API, which provides ways of binding one property to the other. This means that whenever one property's value is changed, the value of the bound property is updated automatically. An example of simple binding: SimpleIntegerProperty first =new SimpleIntegerProperty(5); //create a...