如果我有一个函数，例如将数字转换为数字格式，我显然希望它接受any输入变量并返回对same输入变量的更改。然而，下面不工作，我不知道为什么。我知道如何使用number_format等，但我不知道它如何适合OOP:
Class generic{
public function numeric($num){
if(!is_numeric($num) && !is_float($num)){
throw new Exception("Inputed number is not numeric.");
}
//Convert the input to a number format
$this->num = number_format($num,2);
echo $this->num; // shows a number in the new format..
//Return the input with its new value
$num = $this->num;
return $num;
}
}
class someother class {
//function receiving an array and processing the numbers from it.
public function display_info($data) {
foreach($data->listing as $item) {
$price = $price+$item->price;
}
echo $price; //this shows a number in original format.
//Process $price through the generic class 'numeric' function
generic::numeric($price);
echo '<br/>Total:'.$price.'<br/>'; //This also shows the original format
$output = $this->someotherfunction($price);
return $output;
}
public function someotherfunction($data) {
//Manipulate the data
return $data;
}
}
//Create a new display object to process the pre-existing array $data
$test = new someother();
//Process an array containing
$test->display_info($data);
如果你能帮我理解这个，我将非常感激。
$this->num = $num vs $num = $this->num是如何工作的?
class Generic {
private $num;
public function __construct($num) {
$this->num = $num;
}
public function numeric() {
if(!is_numeric($this->num) && !is_float($this->num)){
throw new Exception("Inputed number is not numeric.");
}
$this->num = number_format($this->num,2);
return $this;
}
public function value() {
return $this->num;
}
}
class OtherClass {
private static function setNum($num) {
return new Generic($num);
}
public function display_info() {
$price = self::setNum(100);
echo '<br/>Total:'.$price->numeric()->value().'<br/>';
}
}
$test = new OtherClass();
$test->display_info();
如果你真的想保持面向对象编程，但我不认为数字交互是面向对象的封闭，但是我在这里所做的。
你的Generic类保存一个数字，你可以修改几个方法，在这种情况下，我们只有numeric()方法。
在你的display方法中，你调用这个类，并设置它的价格值，我硬编码100，但它可以是任何你想要的数值。
当numeric()方法从它的对象中修改$this->num，并返回它的实例时，你可以调用value()方法，它将返回新的修改值。
- 一旦你将值设置为类
- 然后你修改它的方法(
numeric()) 然后将
value()传递给echo输出为:
总:100.00
我的评论中的例子:
class Generic {
private $num;
private $normalized;
public function __construct($num) {
$this->num = $num;
$this->normalized = $num;
}
public function numeric() {
if(!is_numeric($this->num) && !is_float($this->num)){
throw new Exception("Inputed number is not numeric.");
}
$this->num = number_format($this->num,2);
return $this;
}
public function toInt() {
$this->num = intval($this->num);
return $this;
}
public function printR() {
echo "<pre>".print_r($this->num, true)."</pre>";
}
/**
* As normalized was set to the original value of $num and was not modified,
* you will recieve what you have put from the beginning to the constructor
*/
public function normalize() {
$this->num = $this->normalized;
return $this;
}
/**
* You can use this method to retrieve the original value (without calling normalize())
* And you will still have the modified $num, if you want to use it
*/
public function originalValue() {
return $this->normalized;
}
public function value() {
return $this->num;
}
}
class OtherClass {
private static function setNum($num) {
return new Generic($num);
}
public function display_info() {
$price = self::setNum(100);
/**
* numeric() changes it with number_format()
* <pre>100.00</pre>
*/
$price->numeric()->printR();
/**
* toInt() changes it to integer
* <pre>100</pre>
*/
$price->toInt()->printR();
$price->numeric();
/**
* The original value is still kept
* 100
*/
echo $price->originalValue();
/**
* But the object is changed (because of numeric() call)
* 100.00
*/
echo $price->value();
$price->normalize();
/**
* After being normalized to the original value
* 100
*/
echo $price->value();
}
}
您需要了解作用域，以及变量在php中如何传递。泛型类中的函数被传递一个price变量的副本——这个函数不会对其他对象中的原始price变量产生任何影响。
做你想做的事:
Class generic{
//must be static to be called statically
public static function numeric($num){
if(!is_numeric($num) && !is_float($num)){
throw new Exception("Inputed number is not numeric.");
}
return number_format($num,2);
}
}
class someothere{
//function receiving an array and processing the numbers from it.
public function display_info($data) {
foreach($data->listing as $item) {
$price = $price+$item->price;
}
//the generic::numeric function RETURNS a value, it does NOT modify the original
echo '<br/>Total:'.generic::numeric($price).'<br/>';
}
}
如果出于某种原因，您确实希望函数影响原始价格变量，则需要通过引用传递它:
Class generic{
//must be static to be called statically
//notice the & symbol that means that a refernce rather than a copy is passed
public static function numeric(&$num){
if(!is_numeric($num) && !is_float($num)){
throw new Exception("Inputed number is not numeric.");
}
//edits the original variable, no need to return anything
$num = number_format($num,2);
}
}
class someothere{
//function receiving an array and processing the numbers from it.
public function display_info($data) {
foreach($data->listing as $item) {
$price = $price+$item->price;
}
generic::numeric($price);//price is now editied
echo '<br/>Total:'.$price.'<br/>';
}
}