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Using an object-oriented graphing calculator

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Release： 2016-08-08 09:22:43
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This example may not be practical, but it basically summarizes the three characteristics of object-oriented: inheritance, encapsulation, and polymorphism. The main functions of this example are:

  1. Allows the user to select different types of graphics;
  2. Enter the relevant attributes of the selected graphics;
  3. Calculate the perimeter and area of ​​the figure based on the input attributes.

The effect is as follows:

Idea:

    1. Part A is written directly in index.php, and when the corresponding graphic is clicked, a $_GET["shape"] is sent to the own page , using automatic loading classes.
    2. Part B is output by form.class.php, which uses variable functions and uses the value of $_GET["shape"] to call different functions to determine the input part of the form for different graphics.
    3. The C part is output by result.class.php. Declare an abstract class, implement the calculation method of area and perimeter in the abstract class in rect, triangle, circle, reflect inheritance, encapsulation and polymorphism, use new $_GET["shape"]() to instantiate the corresponding Graphics object, and then call the method in the object to return the perimeter and area.

Points for improvement:

  1. This example is only for demonstrating several features of the class. It does not filter the user's input, which may cause injection attacks and is not suitable for actual production applications. In practical applications, user input should be filtered to prevent malicious attacks.
  2. DIV+CSS is not used to optimize the page layout, and the interface is not very friendly. The layout can be optimized and the user experience improved. The

index.php code is as follows: 

<span> 1</span> <html>
<span> 2</span> <head>
<span> 3</span>         <meta http-equiv="charset" c> 4</span> </head>
<span> 5</span> <body>
<span> 6</span>         <div>
<span> 7</span>         <h1>图形周长面积计算器</h1>
<span> 8</span>         <!--点击链接的时候使用GET传递图形的形状属性给index.php,也就是页面本身-->
<span> 9</span>         <a href="index.php?shape=rect">矩形</a>
<span>10</span>         <a href="index.php?shape=triangle">三角形</a>
<span>11</span>         <a href="index.php?shape=circle">圆形</a>
<span>12</span>         </div>
<span>13</span>         <div>
<span>14</span> <?<span>php
</span><span>15</span><span>/*</span><span>自动加载类</span><span>*/</span><span>16</span><span>function</span> __autoload(<span>$className</span><span>){
</span><span>17</span><span>include</span> (<span>strtolower</span>(<span>$className</span>).'.class.php'<span>);
</span><span>18</span><span>        }
</span><span>19</span><span>20</span><span>/*</span><span>21</span><span>        1.先new一个Form对象，发现没有form类的定义，把类名Form传递到自动加载类的函数参数进行类的自动加载。
</span><span>22</span><span>        2.echo一个对象的引用，会调用该对象的__toString方法返回一个字符串，echo输出的就是对象返回的字符串，
</span><span>23</span><span>          这里输出一个表单等待用户的输入。
</span><span>24</span><span>*/</span><span>25</span><span>echo</span><span>new</span> Form("index.php"<span>);
</span><span>26</span><span>27</span><span>/*</span><span>如果用户点击了提交按钮，自动加载result类，输出结果</span><span>*/</span><span>28</span><span>if</span>(<span>isset</span>(<span>$_POST</span>["sub"<span>])){
</span><span>29</span><span>echo</span><span>new</span><span> result();
</span><span>30</span><span>        }
</span><span>31</span> ?>
<span>32</span>         </div>
<span>33</span> </body>
<span>34</span> </html>
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form.class.php code is as follows: 

<span> 1</span> <?<span>php
</span><span> 2</span><span>/*</span><span> 3</span><span>        project:面向对象版图形计算器
</span><span> 4</span><span>        file:form.class.php
</span><span> 5</span><span>        description:对不同的图形输出不同的表单
</span><span> 6</span><span>*/</span><span> 7</span><span>class</span><span> form{
</span><span> 8</span><span>private</span><span>$formAction</span>=<span>NULL</span>;       <span>//</span><span>保存响应表单的文件</span><span> 9</span><span>private</span><span>$shape</span>=<span>NULL</span>;            <span>//</span><span>保存图形的形状</span><span>10</span><span>11</span><span>/*</span><span>12</span><span>                @param string $action 对象初始化传入的参数，代表响应的页面的是哪一个文件
</span><span>13</span><span>*/</span><span>14</span><span>function</span> __construct(<span>$action</span> = ""<span>){
</span><span>15</span><span>$this</span>->formAction = <span>$action</span>;    <span>//</span><span>把传入的参数保存到$formAction中；</span><span>16</span><span>$this</span>->shape = <span>isset</span>(<span>$_GET</span>["shape"]) ? <span>$_GET</span>["shape"]:"rect";   <span>//</span><span>从表单传递的变量中获取图形类别，如没有传递，默认为矩形</span><span>17</span><span>                }
</span><span>18</span><span>function</span><span> __toString(){
</span><span>19</span><span>$form</span> = '<form action="'.<span>$this</span>->formAction.'?shape='.<span>$this</span>->shape.'" method="post">'<span>;
</span><span>20</span><span>//</span><span>下面两行使用变量函数调用对应图形的私有函数，返回input部分表单的字符串</span><span>21</span><span>$shape</span> = 'get'.<span>ucfirst</span>(<span>$this</span>-><span>shape);
</span><span>22</span><span>$form</span> .= <span>$this</span>-><span>$shape</span><span>();
</span><span>23</span><span>24</span><span>$form</span> .= '</br><input type="submit" name="sub" value="计算"/></br>'<span>;
</span><span>25</span><span>$form</span> .= '</form>'<span>;
</span><span>26</span><span>27</span><span>return</span><span>$form</span><span>;
</span><span>28</span><span>                }
</span><span>29</span><span>//</span><span>私有方法，返回矩形表单input部分的字符串；</span><span>30</span><span>private</span><span>function</span><span> getRect(){
</span><span>31</span><span>//</span><span>在表单提交后输入的内容继续显示，防止其消失</span><span>32</span><span>$formheight</span>=<span>isset</span>(<span>$_POST</span>['height']) ? <span>$_POST</span>['height'] : <span>NULL</span><span>;
</span><span>33</span><span>$formwidth</span>=<span>isset</span>(<span>$_POST</span>['width']) ? <span>$_POST</span>['width'] : <span>NULL</span><span>;
</span><span>34</span><span>$input</span> = '<p>请输入矩形的长和宽</p>'<span>;
</span><span>35</span><span>$input</span> .= '矩形的高度：<input type="text" name="height" value="'.<span>$formheight</span>.'"/><br></br>'<span>;
</span><span>36</span><span>$input</span> .= '矩形的宽度：<input type="text" name="width" value="'.<span>$formwidth</span>.'"/></br>'<span>;
</span><span>37</span><span>return</span><span>$input</span><span>;
</span><span>38</span><span>                }
</span><span>39</span><span>//</span><span>返回三角形输入表单input部分的字符串</span><span>40</span><span>private</span><span>function</span><span> getTriangle(){
</span><span>41</span><span>//</span><span>在表单提交后继续显示出来，防止其消失</span><span>42</span><span>$formside1</span>=<span>isset</span>(<span>$_POST</span>['side1']) ? <span>$_POST</span>['side1'] : <span>NULL</span><span>;
</span><span>43</span><span>$formside2</span>=<span>isset</span>(<span>$_POST</span>['side2']) ? <span>$_POST</span>['side2'] : <span>NULL</span><span>;
</span><span>44</span><span>$formside3</span>=<span>isset</span>(<span>$_POST</span>['side3']) ? <span>$_POST</span>['side3'] : <span>NULL</span><span>;
</span><span>45</span><span>$input</span> = '<p>请输入三角形的三边</p>'<span>;
</span><span>46</span><span>$input</span> .= '边长1：<input type="text" name="side1" value="'.<span>$formside1</span>.'" /></br></br>'<span>;
</span><span>47</span><span>$input</span> .= '边长2：<input type="text" name="side2" value="'.<span>$formside2</span>.'"/></br></br>'<span>;
</span><span>48</span><span>$input</span> .= '边长3：<input type="text" name="side3" value="'.<span>$formside3</span>.'"/></br>'<span>;
</span><span>49</span><span>return</span><span>$input</span><span>;
</span><span>50</span><span>                }
</span><span>51</span><span>//</span><span>返回圆形表单input部分的字符串</span><span>52</span><span>private</span><span>function</span><span> getCircle(){
</span><span>53</span><span>$formradius</span>=<span>isset</span>(<span>$_POST</span>['radius']) ? <span>$_POST</span>['radius'] : <span>NULL</span>;  <span>//</span><span>在输入表单提交后内容继续显示出来，防止其消失</span><span>54</span><span>$input</span> = '<p>请输入半径</p>'<span>;
</span><span>55</span><span>$input</span> .= '半径：<input type="text" name="radius" value="'.<span>$formradius</span>.'"/></br>'<span>;
</span><span>56</span><span>return</span><span>$input</span><span>;
</span><span>57</span><span>                }
</span><span>58</span><span>        }
</span><span>59</span>
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The result.class.php code is as follows: 

<span> 1</span> <?<span>php
</span><span> 2</span><span>class</span><span> result{
</span><span> 3</span><span>private</span><span>$shape</span> = <span>NULL</span><span>;
</span><span> 4</span><span> 5</span><span>//</span><span>使用GET传递的变量，实例化一个相应的对象，返回一个对象的引用；</span><span> 6</span><span>function</span><span> __construct(){
</span><span> 7</span><span>$this</span>->shape = <span>new</span><span>$_GET</span>["shape"<span>]();
</span><span> 8</span><span>        }
</span><span> 9</span><span>//</span><span>调用对象的属性和方法，返回周长和面积</span><span>10</span><span>function</span><span> __toString(){
</span><span>11</span><span>$result</span> = <span>$this</span>->shape->shapeName.'的周长为'.<span>$this</span>->shape->perimeter().'</br>'<span>;
</span><span>12</span><span>$result</span> .= <span>$this</span>->shape->shapeName.'的面积为'.<span>$this</span>->shape->area().'</br>'<span>;
</span><span>13</span><span>return</span><span>$result</span><span>;
</span><span>14</span><span>        }
</span><span>15</span> }
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The abstract class shape.class.php code is as follows: 

<span> 1</span> <?<span>php
</span><span> 2</span><span>/*</span><span> 3</span><span>        project:面向对象版图形计算器
</span><span> 4</span><span>        file:shape.class.php
</span><span> 5</span><span>        description:抽象类，定义两个抽象方法area()和perimeter(),以及定义方法validate对输入的值进行验证
</span><span> 6</span><span>*/</span><span> 7</span><span>abstract</span><span>class</span><span> shape{
</span><span> 8</span><span>public</span><span>$shapeName</span>;                      <span>//</span><span>形状名称；</span><span> 9</span><span>abstract</span><span>function</span> area();               <span>//</span><span>抽象类area(),让子类去实现，体现多态性</span><span>10</span><span>abstract</span><span>function</span> perimeter();          <span>//</span><span>抽象类perimeter();</span><span>11</span><span>12</span><span>/*</span><span>13</span><span>                @param mixed $value 接受表单输入值
</span><span>14</span><span>                @param string $message 提示消息前缀
</span><span>15</span><span>                @param boolean 返回值，成功为TRUE，失败为FALSE
</span><span>16</span><span>*/</span><span>17</span><span>protected</span><span>function</span> validate(<span>$value</span>,<span>$message</span> = "输入的值"<span>){
</span><span>18</span><span>if</span>(<span>$value</span> < 0 || <span>$value</span> == <span>NULL</span> || !<span>is_numeric</span>(<span>$value</span><span>)){
</span><span>19</span><span>$message</span> = <span>$this</span>->shapeName.<span>$message</span><span>;
</span><span>20</span><span>echo</span> '<font color="red">'.<span>$message</span>.'必须为正数</font><br>'<span>;
</span><span>21</span><span>return</span><span>FALSE</span><span>;
</span><span>22</span><span>                }
</span><span>23</span><span>else</span><span>24</span><span>return</span><span>TRUE</span><span>;
</span><span>25</span><span>        }
</span><span>26</span> }
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The subclass triangle.class.php code is as follows: 

<span> 1</span> <?<span>php
</span><span> 2</span><span>/*</span><span>*
</span><span> 3</span><span>        project:面向对象版图形计算器
</span><span> 4</span><span>        file:triangle.class.php
</span><span> 5</span><span>        description：继承抽象类shape，计算并返回三角形的周长和面积
</span><span> 6</span><span>*/</span><span> 7</span><span>class</span> triangle <span>extends</span><span> shape{
</span><span> 8</span><span>private</span><span>$side1</span> = 0;             <span>//</span><span>边长1；</span><span> 9</span><span>private</span><span>$side2</span> = 0;             <span>//</span><span>边长2；</span><span>10</span><span>private</span><span>$side3</span> = 0;             <span>//</span><span>边长3；</span><span>11</span><span>12</span><span>/*</span><span>13</span><span>                构造函数：对表单变量进行合理性验证，通过则初始化三个边长
</span><span>14</span><span>*/</span><span>15</span><span>function</span><span> __construct(){
</span><span>16</span><span>$this</span>->shapeName = "三角形";    <span>//</span><span>命名图形
</span><span>17</span><span>18</span><span>                //使用父类的方法validate检查输入的是否为正数</span><span>19</span><span>if</span>(<span>$this</span>->validate(<span>$_POST</span>["side1"],"边长1") & <span>$this</span>->validate(<span>$_POST</span>["side2"],"边长2") & <span>$this</span>->validate(<span>$_POST</span>["side3"],"边长3"<span>)){
</span><span>20</span><span>21</span><span>//</span><span>使用私有方法验证两边和是否大于第三边</span><span>22</span><span>if</span>(<span>$this</span>->validatesum(<span>$_POST</span>["side1"],<span>$_POST</span>["side2"],<span>$_POST</span>["side3"<span>])){
</span><span>23</span><span>$this</span>->side1 = <span>$_POST</span>["side1"];         <span>//</span><span>若通过验证初始化三边；</span><span>24</span><span>$this</span>->side2 = <span>$_POST</span>["side2"<span>];
</span><span>25</span><span>$this</span>->side3 = <span>$_POST</span>["side3"<span>];
</span><span>26</span><span>                        }
</span><span>27</span><span>else</span><span>{
</span><span>28</span><span>echo</span> '<font color="red">两边的和要大于第三边</font>'<span>;
</span><span>29</span><span>exit</span><span>();
</span><span>30</span><span>                        }
</span><span>31</span><span>                }
</span><span>32</span><span>else</span><span>{
</span><span>33</span><span>exit</span><span>();
</span><span>34</span><span>                }
</span><span>35</span><span>        }
</span><span>36</span><span>/*</span><span>使用海伦公式计算面积,并返回结果</span><span>*/</span><span>37</span><span>function</span><span> area(){
</span><span>38</span><span>$s</span> = (<span>$_POST</span>["side1"] + <span>$_POST</span>["side2"] + <span>$_POST</span>["side3"])/2<span>;
</span><span>39</span><span>return</span><span>sqrt</span>(<span>$s</span> * (<span>$s</span> - <span>$_POST</span>["side1"]) * (<span>$s</span> - <span>$_POST</span>["side2"]) * (<span>$s</span> - <span>$_POST</span>["side3"<span>]));
</span><span>40</span><span>        }
</span><span>41</span><span>/*</span><span>计算并返回周长</span><span>*/</span><span>42</span><span>function</span><span> perimeter(){
</span><span>43</span><span>return</span><span>$_POST</span>["side1"] + <span>$_POST</span>["side2"] + <span>$_POST</span>["side3"<span>];
</span><span>44</span><span>        }
</span><span>45</span><span>/*</span><span>计算三角形两边和是否大于第三边，是返回TRUE，否返回FALSE</span><span>*/</span><span>46</span><span>private</span><span>function</span> validatesum(<span>$side1</span>,<span>$side2</span>,<span>$side3</span><span>){
</span><span>47</span><span>if</span>((<span>$side1</span> + <span>$side2</span>) > <span>$side3</span> && (<span>$side1</span> + <span>$side3</span>) > <span>$side2</span> && (<span>$side2</span> + <span>$side3</span>) > <span>$side1</span><span>)
</span><span>48</span><span>return</span><span>TRUE</span><span>;
</span><span>49</span><span>else</span><span>50</span><span>return</span><span>FALSE</span><span>;
</span><span>51</span><span>        }
</span><span>52</span> }
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The subclass circle.class.php code is as follows: 

<span> 1</span> <?<span>php
</span><span> 2</span><span>/*</span><span> 3</span><span>        project:面向对象的图形计算器
</span><span> 4</span><span>        file:circle.class.php
</span><span> 5</span><span>        description:接收表单值，返回周长和面积
</span><span> 6</span><span>*/</span><span> 7</span><span>class</span> circle <span>extends</span><span> shape{
</span><span> 8</span><span>private</span><span>$radius</span>;        <span>//</span><span>圆的半径
</span><span> 9</span><span>10</span><span>        //初始化圆的名称，检查输入合法性并初始化半径</span><span>11</span><span>function</span><span> __construct(){
</span><span>12</span><span>$this</span>->shapeName = "圆形"<span>;
</span><span>13</span><span>if</span>(<span>$this</span>->validate(<span>$_POST</span>["radius"],"半径"<span>))
</span><span>14</span><span>$this</span>->radius = <span>$_POST</span>["radius"<span>];
</span><span>15</span><span>        }
</span><span>16</span><span>//</span><span>返回圆的面积</span><span>17</span><span>function</span><span> area(){
</span><span>18</span><span>return</span> 3.14 * <span>$this</span>->radius * <span>$this</span>-><span>radius;
</span><span>19</span><span>        }
</span><span>20</span><span>//</span><span>返回圆的周长</span><span>21</span><span>function</span><span> perimeter(){
</span><span>22</span><span>return</span> 3.14 * 2 * <span>$this</span>-><span>radius;
</span><span>23</span><span>        }
</span><span>24</span> }
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The subclass rect.class.php code is as follows: 

<span> 1</span> <?<span>php
</span><span> 2</span><span>/*</span><span> 3</span><span>        project:面向对象的图形计算器
</span><span> 4</span><span>        file:rect.class.php
</span><span> 5</span><span>        descrition:声明一个矩形资料，实现形状抽象类计算周长和面积的方法，返回矩形的周长和面积
</span><span> 6</span><span>*/</span><span> 7</span><span>class</span> rect <span>extends</span><span> shape{
</span><span> 8</span><span>private</span><span>$width</span>;         <span>//</span><span>矩形的宽度</span><span> 9</span><span>private</span><span>$height</span>;        <span>//</span><span>矩形的高度
</span><span>10</span><span>11</span><span>        //使用父类的validate方法验证输入的合法性，通过则初始化宽度和高度</span><span>12</span><span>function</span><span> __construct(){
</span><span>13</span><span>$this</span>->shapeName = "矩形"<span>;
</span><span>14</span><span>if</span>(<span>$this</span>->validate(<span>$_POST</span>["width"],"宽度") && <span>$this</span>->validate(<span>$_POST</span>["height"],"高度"<span>)){
</span><span>15</span><span>$this</span>->width = <span>$_POST</span>["width"<span>];
</span><span>16</span><span>$this</span>->height = <span>$_POST</span>["height"<span>];
</span><span>17</span><span>        }
</span><span>18</span><span>        }
</span><span>19</span><span>//</span><span>返回面积</span><span>20</span><span>function</span><span> area(){
</span><span>21</span><span>return</span><span>$this</span>->width * <span>$this</span>-><span>height;
</span><span>22</span><span>        }
</span><span>23</span><span>//</span><span>返回周长</span><span>24</span><span>function</span><span> perimeter(){
</span><span>25</span><span>return</span> 2 * (<span>$this</span>->width + <span>$this</span>-><span>height);
</span><span>26</span><span>        }
</span><span>27</span> }
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　　1. This article is only suitable for experiments and is not suitable for real-life applications. I am not responsible for any adverse consequences.

　　2. This article is an original blog and can be freely reproduced on personal platforms, but the source needs to be indicated and a link attached, otherwise it will be regarded as plagiarism. Commercial use is strictly prohibited. If necessary, please contact me to pay the manuscript fee and obtain authorization before use.

The above has introduced the use of object-oriented graphing calculator, including aspects of the content. I hope it will be helpful to friends who are interested in PHP tutorials.

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