Tutorial by Examples: f

A computed column is computed from an expression that can use other columns in the same table. The expression can be a noncomputed column name, constant, function, and any combination of these connected by one or more operators. Create table with a computed column Create table NetProfit ( Sa...

You can overload a def if the signature is different: def printValue(x: Int) { println(s"My value is an integer equal to $x") } def printValue(x: String) { println(s"My value is a string equal to '$x'") } printValue(1) // prints "My value is an integer equal ...

There are a few ways to inspect the contents of a zipfile. You can use the printdir to just get a variety of information sent to stdout with zipfile.ZipFile(filename) as zip: zip.printdir() # Out: # File Name Modified Size ...

Sometimes, one wants to run some initialization code once before testing a condition. In certain other languages, this kind of loop has special do-while syntax. However, this syntax can be replaced with a regular while loop and break statement, so Julia does not have specialized do-while syntax. Ins...

0.5.0 (Although this example is written using syntax introduced in version v0.5, it can work with few modifications on older versions also.) This implementation of breadth-first search (BFS) on a graph represented with adjacency lists uses while loops and the return statement. The task we will sol...

% set mypath /home/tcluser/sources/tcl/myproject/test.tcl /home/tcluser/sources/tcl/myproject/test.tcl % set dir [file dirname $mypath] /home/tcluser/sources/tcl/myproject % set filename [file tail $mypath] test.tcl % set basefilename [file rootname $filename] test % set extension [file exte...

Consider the following code snippet: // Print the sum of the numbers 1 to 10 int count = 0; for (int i = 1; i < 010; i++) { // Mistake here .... count = count + i; } System.out.println("The sum of 1 to 10 is " + count); A Java beginner might be surprised to know that the...

The javadoc for the Thread class shows two ways to define and use a thread: Using a custom thread class: class PrimeThread extends Thread { long minPrime; PrimeThread(long minPrime) { this.minPrime = minPrime; } public void run() { // compute primes l...

Jumping out of nested loops would usually require use of a boolean variable with a check for this variable in the loops. Supposing we are iterating over i and j, it could look like this size_t i,j; for (i = 0; i < myValue && !breakout_condition; ++i) { for (j = 0; j < mySecondVa...

A lot of people who are new to multi-threading think that using threads automatically make an application go faster. In fact, it is a lot more complicated than that. But one thing that we can state with certainty is that for any computer there is a limit on the number of threads that can be run at ...

When programming in Prolog it is not always possible, or desirable, to create predicates which unify for every possible combination of parameters. For example, the predicate between(X,Y,Z) which expresses that Z is numerically between X and Y. It is easily implemented in the cases where X, Y, and Z ...

You can take a look at the full code in this working Plunker. In this example I use a shared service to handle the communication between the pages inside the tab (child pages) and the tab container (the component that holds the tabs). Even though you probably could do it with Events I like the shar...

Sometimes, programmers who are new to Java make the mistake of defining a class with a name that is the same as a widely used class. For example: package com.example; /** * My string utilities */ public class String { .... } Then they wonder why they get unexpected errors. For ex...

Render a white rectangle over an image with the composite operation ctx.globalCompositeOperation = 'difference'; The amount of the effect can be controled with the alpha setting // Render the image ctx.globalCompositeOperation='source-atop'; ctx.drawImage(image, 0, 0); // set the composite...

Create a colored sepia FX with ctx.globalCompositeOperation = 'luminosity'; In this case the sepia colour is rendered first the the image. The amount of the effect can be controled with the alpha setting or the amount of saturation in the fill overlay // Render the image ctx.globalCompositeOp...

You can use a filter to log only messages "lower" than e.g. ERROR level. But the filter is not supported by PropertyConfigurator. So you must change to XML config to use it. See log4j-Wiki about filters. Example "specific level" <appender name="info-out" class=&quo...

In order to prevent a button from firing multiple times within a short period of time (let's say 2 clicks within 1 second, which may cause serious problems if the flow is not controlled), one can implement a custom SingleClickListener. This ClickListener sets a specific time interval as threshold (...

PrepareForSegue: func prepareForSegue(_ segue:UIStoryboardSegue, sender sender:AnyObject?) Notifies the view controller that a segue is about to be performed Parameters segue: The segue object. sender: The object that initialized the segue. Example in Swift Perform a task if the ident...

ShouldPerformSegueWithIdentifier: func shouldPerformSegueWithIdentifier(_ identifier:String, sender sender:AnyObject?) -> Bool Determines whether the segue with the specified identifier should be performed. Parameters Identifier: String that identifies the triggered segue Sender: The...

Every instance of WWW with a second parameter is a post. Here is an example to post user id and password to server. void Login(string id, string pwd) { WWWForm dataParameters = new WWWForm(); // Create a new form. dataParameters.AddField("username", id); dataParameter...