Yaodong Zhao yaodong

In PHP, You can set default value for variables use ?: if value contains fasle value or undefined.

$value = null;
$value = $value ?: "default";
echo $value; // get "default"

Another way is:

From Best Practices for Speeding Up Your Web Site:

When the browser makes a request for a static image and sends cookies together with the request, the server doesn't have any use for those cookies. So they only create network traffic for no good reason. You should make sure static components are requested with cookie-free requests. Create a subdomain and host all your static components there.

If your domain is www.example.org, you can host your static components on static.example.org. However, if you've already set cookies on the top-level domain example.org as opposed to www.example.org, then all the requests to static.example.org will include those cookies. In this case, you can buy a whole new domain, host your static components there, and keep this domain cookie-free. Yahoo! uses yimg.com, YouTube uses ytimg.com, Amazon uses images-amazon.com and so on.

Another benefit of hosting static components on a cookie-free domain is that som

From StackOverflow:

The statement does not evaluate to a value and can be used on its own, while the expression needs to be a part of an expression.

CASE expression:

SELECT CASE
    WHEN type = 1 THEN 'foo'
    WHEN type = 2 THEN 'bar'

From WikiPedia:

A parity bit, or check bit is a bit added to the end of a string of binary code that indicates whether the number of bits in the string with the value one is even or odd. Parity bits are used as the simplest form of error detecting code.

There are two variants of parity bits: even parity bit and odd parity bit.

In the case of even parity, the number of bits whose value is 1 in a given set are counted. If that total is odd, the parity bit value is set to 1, making the total count of 1's in the set an even number. If the count of ones in a given set of bits is already even, the parity bit's value remains 0.

From stackoverflow:

Marketing hype (and cost). This is not part of the spec.

From Wikipedia:

VeriSign uses the concept of classes for different types of digital certificates :

Class 1 for individuals, intended for email.
Class 2 for organizations, for which proof of identity is required.

From stackoverflow:

Marketing hype (and cost). This is not part of the spec.

From Wikipedia:

VeriSign uses the concept of classes for different types of digital certificates :

Class 1 for individuals, intended for email.
Class 2 for organizations, for which proof of identity is required.

From PsychWiki:

Memory is a good indicator as to whether people continue to be interrupted by thoughts of incomplete tasks. Constant thoughts of incomplete task components cause it to be retained in memory better. Interruptions that cause a person to fall behind in their objective also cause anxiety that brings about constant thoughts of unfinished business.

Apdex (Application Performance Index) is an open standard developed by an alliance of companies. It defines a standard method for reporting and comparing the performance of software applications in computing. Its purpose is to convert measurements into insights about user satisfaction, by specifying a uniform way to analyze and report on the degree to which measured performance meets user expectations.

The Apdex formula is the number of satisfied samples plus half of the tolerating samples plus none of the frustrated samples, divided by all the samples:

Apdext = (Satisfied Count + Tolerating Count / 2) / Total Samples

From Wikipedia:

In mathematics and computer science, a higher-order function (also functional form, functional or functor) is a function that does at least one of the following:

takes one or more functions as an input

outputs a function

Related to:

	instance of
	┌──────┐
	▼ │
	┌─────────┐ instance of ┌────────┐ instance of ┌───────┐ │
	│ "hello" │──────────────▶│ String │──────────────▶│ Class │──┘
	└─────────┘ └────────┘ └───────┘