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Complete inheritance and object method demonstration
Objects in PHP example from a Well House Consultants training course
More on Objects in PHP [link]

This example is described in the following article(s):
   • Sorting objects in PHP - [link]

Source code: compo.php Module: H108

/* A demonstration of Object Oriention in PHP5 showing some key elements

A. A base class "Transact".
B. Extended to two subclasses "Income" and "Spend"

1. Polymorphic constructors
2. An array of objects based on type "Transact"
3. Comparator functions to compare 2 objects, and also
   to compare a whole array of objects
4. A user sort of a whole array of objects


class transact {

        /* A Class of financial transactions */

        protected $amount;
        protected $about;

        function getvalue() {
                return $this->amount; }
        function getabout() {
                return $this->about; }
        function morevaluable($that) {
                if ($this->getvalue() > $that->getvalue()) {
                        return $this ;
                return $that;
        static function mostvaluable($thems) {
                $bsf = $thems[0];
                foreach ($thems as $other) {
                        $bsf = $bsf->morevaluable($other);
                return $bsf;
        static function mvf($first,$second) {
                if ($first->getvalue() > $second->getvalue()) return 1;
                if ($first->getvalue() < $second->getvalue()) return -1;
                return 0;

/* Income and expenditure classes, based on the
generic transaction */

class income extends transact {
        function __construct($owmuch,$whom) {
                $this->amount = $owmuch;
                $this->about = $whom; }
class spend extends transact {
        function __construct($amount,$whom) {
                $this->amount = -$amount;
                $this->about = $whom; }

/* ------------------------------------------ */

/* Main application (test program) reading in a tab separated
set of accounts */

$wellhousemanor = array();
foreach (file("sage.xls") as $line) {
        list($val,$type,$desc) = explode("\t",trim($line));

        /* We have to know what each object is as we create it */

        switch ($type) {
        case "income":
                array_push($wellhousemanor,new income($val,$desc));
        case "excome":
                array_push($wellhousemanor,new spend($val,$desc));
                /* World's worst error handler */
                print "Your data is busted\n";

/* Polymorphic use of objects we have created */

$runbal = 0;
foreach ($wellhousemanor as $line) {
        $runbal += ($vp = $line->getvalue());
        print ("Value $vp, balance $runbal, after ".$line->getabout()."\n");

/* Example of how we call the comparators */

$better = $wellhousemanor[0]->morevaluable($wellhousemanor[3]);
print ("The better one is ". $better->getabout() ."\n");

$best = transact::mostvaluable($wellhousemanor);
print ("The best one is ". $best->getabout() ."\n");

/* How to sort an array of objects based on a class method */


/* Output sorted results to test / prove correct operation */

foreach ($wellhousemanor as $line) {
        $runbal += ($vp = $line->getvalue());
        print ("Value $vp, balance $runbal, after ".$line->getabout()."\n");

/* Sample data file

175.00 income John Smith
190.66 income Ahmed Patel
12.10 income Frugal McScot
12.34 dunno Fred Brown
100.00 excome Event Manager
150.00 excome UTAHs


/* Sample output

Dorothy:oct08 grahamellis$ php compo.php
Your data is busted
Value 175.00, balance 175, after John Smith
Value 190.66, balance 365.66, after Ahmed Patel
Value 12.10, balance 377.76, after Frugal McScot
Value -100, balance 277.76, after Event Manager
Value -150, balance 127.76, after UTAHs
The better one is John Smith
The best one is Ahmed Patel
Value -150, balance -22.24, after UTAHs
Value -100, balance -122.24, after Event Manager
Value 12.10, balance -110.14, after Frugal McScot
Value 175.00, balance 64.86, after John Smith
Value 190.66, balance 255.52, after Ahmed Patel
Dorothy:oct08 grahamellis$


Learn about this subject
This module and example are covered on the following public courses:
 * Object Oriented Programming in PHP
 * PHP Programming
 * Learning to program in PHP
Also available on on site courses for larger groups

Books covering this topic
Yes. We have over 700 books in our library. Books covering PHP are listed here and when you've selected a relevant book we'll link you on to Amazon to order.

Other Examples
This example comes from our "Objects in PHP" training module. You'll find a description of the topic and some other closely related examples on the "Objects in PHP" module index page.

Full description of the source code
You can learn more about this example on the training courses listed on this page, on which you'll be given a full set of training notes.

Many other training modules are available for download (for limited use) from our download centre under an Open Training Notes License.

Other resources
• Our Solutions centre provides a number of longer technical articles.
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