PHP变量及变量作用域 php打印变量 php的变量和常量 php所有变

   新学PHP，比较有意思的语法，记录下。

1. 变量的作用域

   作用域只分两个Global和Local，Global相对于整个.php文件来讲，Local是本地最小范围，是距离变量最近的范围，如：在函数中，在类中等。

2. 变量的声明

    可能是由于PHP变量独特的$符号，所以声明PHP变量不需要关键字（类中除外），第一次赋值的时候自动创建了。

    类中却比较独特了，由于类带有成员属性private、public、protected，那么在类中声明变量的时候是需要关键字修饰的。用前面所说的关键字或这个关键字var，但是不可以二者共用。

3. 样例说明

<span> 1</span> <span>php
</span><span> 2</span><span> 3</span><span>$VarFile</span> = "Var_File";   <span>//</span><span>变量声明</span><span> 4</span><span> 5</span><span>$nr</span> = <span>array</span>("\n","\r","\n\r","\r\n"<span>);
</span><span> 6</span><span> 7</span><span> 8</span><span>class</span><span> TestClass
</span><span> 9</span><span>{    
</span><span>10</span><span>/*</span><span>11</span><span>    *    分别用Var声明和private关键字声明
</span><span>12</span><span>    *   $var = value; 这种不可以
</span><span>13</span><span>    *    var private $var; 这种不可以
</span><span>14</span><span>    *    var private $var = value; 这种不可以
</span><span>15</span><span>    *    var $var; 这种不可以    
</span><span>16</span><span>*/</span><span>17</span><span>18</span><span>var</span><span>$VarClass</span> = 'VarClass declared by keyword Var'<span>;            
</span><span>19</span><span>private</span><span>$VarClass2</span> = 'VarClass2 declared by keyword private'<span>;
</span><span>20</span><span>21</span><span>/*</span><span>22</span><span>    *    增加global关键字，使用global作用域的变量
</span><span>23</span><span>    *   函数中声明变量方法与全局一样
</span><span>24</span><span>*/</span><span>25</span><span>26</span><span>function</span><span> GetAllVar() {
</span><span>27</span><span>global</span><span>$VarFile</span><span>;
</span><span>28</span><span>$VarFunction</span> = 'Var_Function'<span>;
</span><span>29</span><span>30</span><span>$Temp</span> = "<span>$VarFile</span>=".<span>$VarFile</span>."\r\n".
<span>31</span>                 "VarClass=".<span>$this</span>->VarClass."\r\n".
<span>32</span>                 "VarClass2=".<span>$this</span>->VarClass2."\r\n".
<span>33</span>                 "VarFunction=".<span>$VarFunction</span>."\r\n"<span>;
</span><span>34</span><span>35</span><span>36</span><span>return</span><span>str_replace</span>(<span>$GLOBALS</span>['nr'],"<br>",<span>$Temp</span><span>);
</span><span>37</span><span>    }
</span><span>38</span><span>39</span><span>40</span><span>41</span><span>}
</span><span>42</span><span>43</span><span>$MyClass</span> = <span>new</span> TestClass("zzy"<span>);
</span><span>44</span><span>echo</span><span>$MyClass</span>-><span>GetAllVar();
</span><span>45</span><span>46</span> ?>

　 

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