How to display errors on php web pages?
To debug .php web pages, you want to print something on the browser’s windows when opening the web pages. You can use the php echo or print function to display […]
How to protect web page from being copied using javascript?
Some stupid websites may use javascript to disable copy/paste. You can not select the text on their website. You can not use Ctrl C to copy content from the webpage. […]
The first parameter of setTimeout in javascript
I often got confused by different usages of the setTimeout function. I do not know where I got the following usage, which is proven not the correct usage: setTimeout(“alert(‘hello world’)”,1000); […]
import wildcard, import specific class and class search order
Today, I got a problem compiling a java source code. The source code uses several classes in another package so I use “import fruit.*” to try to import all classes […]
public, private, package, protected in Java
In Java, class members can be declared with public, private, protected, or nothing. If you need to access a member from another package (even from a derived class)using obj.membername, the […]
difference between protected in C++ and protected in Java
In C++, protected members cannot be accessed outside the class and its derived classes using obj.membername #include <QtCore> //#include “windows.h” //#include <QApplication> class A { public: void fun() { qDebug()<<“a”; […]
public,private,protected in C++
When talking about public,private, and protected in C++, two words must pop up in your head:accessibility and visibility. Unfortunately, the two academic words are just created to confuse learners as […]
java compile and execution
Let’s compile a simple java program in current directory(javac Test.java): //Test.java class Test { String a=”hello”; public static void main(String[]args) { Test b=new Test(); b.a=”world”; System.out.println(b.a); App app=new App(); app.fun(); […]
How to center a button using CSS?
Button is an inline element. It can not be centered using the “margin:auto;” that is for block element. Even if you set “display:inline-block” for it, the “margin:auto;” still has no […]
The default height and width of empty div in CSS
The height and width CSS properties are not inheritable. If not specified, their default value is “auto” which means “browser will calculate it“. But how does the browser calculate the […]