Notes for Web Technologies Through PHP Exam -CSIB Continued

Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects", which are data structures that contain data, in the form of fields, often known as attributes; and code, in the form of procedures, often known as methods. A distinguishing feature of objects is that an object's procedures can access and often modify the data fields of the object with which they are associated (objects have a notion of "this"). that interact with one another


PHP String Operators

PHP has two operators that are specially designed for strings.
Operator     Name               Example                         Result   
.                 Concatenation     $txt1.$txt2     Concatenation of $txt1 and $txt2    
.=   Concatenation assignment     $txt1 .= $txt2     Appends $txt2 to $txt1

. is used for the concatenation of two strings usually.

PHP - Sort Functions For Arrays

In this chapter, we will go through the following PHP array sort functions:

    sort() - sort arrays in ascending order
    rsort() - sort arrays in descending order
    asort() - sort associative arrays in ascending order, according to the value
    ksort() - sort associative arrays in ascending order, according to the key
    arsort() - sort associative arrays in descending order, according to the value
    krsort() - sort associative arrays in descending order, according to the key

Create an Array in PHP

In PHP, the array() function is used to create an array:
array();

In PHP, there are three types of arrays:

    Indexed arrays - Arrays with a numeric index
    Associative arrays - Arrays with named keys
    Multidimensional arrays - Arrays containing one or more arrays

PHP Indexed Arrays

There are two ways to create indexed arrays:

The index can be assigned automatically (index always starts at 0), like this:
$cars = array("Volvo", "BMW", "Toyota");

or the index can be assigned manually:
$cars[0] = "Volvo";
$cars[1] = "BMW";
$cars[2] = "Toyota";

The following example creates an indexed array named $cars, assigns three elements to it, and then prints a text containing the array values:
Example
$cars = array("Volvo", "BMW", "Toyota");
echo "I like " . $cars[0] . ", " . $cars[1] . " and " . $cars[2] . ".";
?>


PHP Associative Arrays

Associative arrays are arrays that use named keys that you assign to them.
There are two ways to create an associative array:
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");

or:
$age['Peter'] = "35";
$age['Ben'] = "37";
$age['Joe'] = "43";

The named keys can then be used in a script:
Example
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
echo "Peter is " . $age['Peter'] . " years old.";
?>