服务端 - PHP - 基础知识之变量、常量和数据类型

一、变量

1. 概述

2. 可变变量

3. 私有变量

4. 静态变量

5. 全局变量

6. 超全局变量

7. 变量过滤器

8. 代码示例

1. php
3. echo '

   ';

4. echo "一、使用静态变量实现累加效果";
5. echo'';
7. $sum = function() {
8. static $n = 0;
9. $n += 1;
10. return $n;
11. };
13. echo $sum();
14. echo '
';
15. echo $sum();
16. echo '
';
17. echo $sum();
18. echo '
';
19. echo '

    ---

    ';
21. echo '

    ';

22. echo "二、函数作用域内使用全局变量的方式";
23. echo'';
25. echo '

    ';

26. echo "1. 使用global关键字";
27. echo'';
29. $name = "小明1";
30. echo "我的名字叫" . $name;
31. function sayMyName1() {
32. global $name;
33. $name = "小红1";
34. echo '
';
35. echo "我的名字叫" . $name;
36. }
37. echo sayMyName1();
39. echo '

    ';

40. echo "2. 使用\$GLOBALS超全局变量数组";
41. echo'';
43. $name = "小明2";
44. echo "我的名字叫" . $name;
45. function sayMyName2() {
46. $GLOBALS['name'] = "小红2";
47. echo '
';
48. echo "我的名字叫" . $GLOBALS['name'];
49. }
50. echo sayMyName2();
51. echo '

    ---

    ';
53. echo '

    ';

54. echo "三、使用变量过滤器过滤变量";
55. echo'';
57. echo '

    ';

58. echo "1. 过滤单个变量";
59. echo'';
61. $n = 10;
62. if (filter_var($n, 257)) :
63. echo "已过滤1";
64. else :
65. echo "error2";
66. endif;
67. echo '
';
68. $n = 10.2;
69. if (filter_var($n, 257)) :
70. echo "已过滤1";
71. else :
72. echo "error2";
73. endif;
75. echo '

    ';

76. echo "2. 同时过滤多个变量";
77. echo'';
79. echo "全部变量过滤成功";
80. $data = ["name"=>"Peter", "age"=>12, "email"=>"xiaoming@qq.com"];
81. $filters = [
82. "name"=>["filter"=>FILTER_VALIDATE_REGEXP, "options"=>["regexp"=>"/^P(.*)/"]],
83. "age"=>["filter"=>FILTER_VALIDATE_INT, "options"=>["min_range"=>10, "max_range"=>15]],
84. "email"=>FILTER_VALIDATE_EMAIL
85. ];
86. echo '

    ';

87. print_r(filter_var_array($data, $filters));
88. echo '';
90. echo "\$name变量过滤失败";
91. $data = ["name"=>"peter", "age"=>12, "email"=>"xiaoming@qq.com"];
92. $filters = [
93. "name"=>["filter"=>FILTER_VALIDATE_REGEXP, "options"=>["regexp"=>"/^P(.*)/"]],
94. "age"=>["filter"=>FILTER_VALIDATE_INT, "options"=>["min_range"=>10, "max_range"=>15]],
95. "email"=>FILTER_VALIDATE_EMAIL
96. ];
97. echo '

    ';

98. print_r(filter_var_array($data, $filters));
99. echo '';
101. echo '

     ';

102. echo "3. 显示所有过滤器ID";
103. echo'';
105. echo '';
     foreach (filter_list() as $key => $value) {
     echo '
     '.''.''.'';
     }
     echo '

     '.$value.'

     '.filter_id($value).'

     ';
106. ?>