How eval works

Reference: http://www.phpchina.com/bbs/thread-25541-1-15.html

 

In this example, Eval is used to store array elements on a pay-as-you-go basis for unlimited classification.

 

1. Class m_layer {
2. /**
3. * Unlimited Classification
4. *
5. * @ Param object $ MDB
6. * @ Param string $ table
7. * @ Param string $ label_colum
8. * @ Return Array
9. */
10. Function get_layer ($ layer, $ label_colum = 'label '){
11. $ New_layer = array ();
13. If (! Is_array ($ layer) |! Is_array (current ($ layer) |! Array_key_exists ($ label_colum, current ($ layer ))){
14. Return array ();
15. }
16. Foreach ($ layer as $ row ){
17. $ Row_str = '';
18. Foreach ($ row as $ key => $ value ){
19. $ Row_str. = ", '$ key' =>' $ value '";
20. }
21. $ Row_str = "array (". substr ($ row_str, 1 ).')';
23. $ Label_arr = explode ('-', $ row [$ label_colum]);
24. $ Layer_str = '$ new_layer ';
25. Foreach ($ label_arr as $ label ){
26. If (intval ($ label )){
27. $ Layer_str. = "['child '] [' $ label']";
28. }
29. }
31. Eval ("$ layer_str = $ row_str; echo strip_tags (/"/$ layer_str =/$ row_str /");");
32. Echo '<br/> ';
33. }
34. Return $ new_layer ['child '];
35. }
37. /**
38. * Getting a new layer is equivalent to mysql_insert_id.
39. *
40. * @ Param object $ MDB
41. * @ Param string $ table
42. * @ Param string $ father_label
43. * @ Param string $ label_colum
44. * @ Return Array
45. */
46. Function get_new_layer ($ mdb, $ table, $ father_label, $ label_colum = 'labe '){
47. $ COUNT = $ father_label? Count (explode ('-', $ father_label): 0;
48. $ Size = strlen ($ father_label );
49. $ SQL = "select $ label_colum from $ table where left ($ label_colum, $ size) = '$ father_label' order by $ label_colum DESC ";
50. $ Rs = $ MDB-> fetch_row ($ SQL );
51. $ Last_label_arr = explode ('-', $ Rs [$ label_colum]);
52. $ Last_label = '';
53. For ($ I = 0; $ I <= $ count; $ I ++ ){
54. $ Last_label. = '-'. $ last_label_arr [$ I];
55. }
56. $ Last_label = substr ($ last_label, 1 );
57. $ New_label = explode ('-', $ last_label );
58. $ Num = array_pop ($ new_label );
59. $ New_label = implode ('-', $ new_label). '-'. ++ $ num;
60. Return $ new_label;
61. }
62. }
63. $ Label [] = array ('name' => 'family of games ', 'lay' => '01 ');
64. $ Label [] = array ('name' => 'Online game', 'lay' => '01-01 ');
65. $ Label [] = array ('name' => 'kart ', 'lay' => '01-01-01 ');
66. $ Label [] = array ('name' => 'bubble thup', 'lay' => '01-01-02 ');
67. $ Label [] = array ('name' => 'standalone game', 'lay' => '01-02 ');
68. $ Label [] = array ('name' => 'resident evil ', 'lay' => '01-02-01 ');
69. $ Label [] = array ('name' => 'death squads ', 'lay' => '01-02-02 ');
70. $ Label [] = array ('name' => 'super Mary', 'lay' => '01-02-02 ');
71. $ Label [] = array ('name' => 'entertainment & Leisure ', 'lay' => '02 ');
72. $ Label [] = array ('name' => 'music home', 'lay' => '02-01 ');
73. $ Label [] = array ('name' => 'Jay Chou ', 'lay' => '02-01-01 ');
74. $ Label [] = array ('name' => 'Liu ruoying ', 'layer' => '02-01-02 ');
75. $ Label [] = array ('name' => 'scholarly door', 'lay' => '02-02 ');
76. $ Label [] = array ('name' => 'fiction ', 'lay' => '02-02-01 ');
77. $ Label [] = array ('name' => 'novels ', 'lay' => '02-02-01-01 ');
78. $ Label [] = array ('name' => 'short story ', 'lay' => '02-02-01-02 ');
79. $ Label [] = array ('name' => 'journal ', 'lay' => '02-02-02 ');
80. $ Layeray = m_layer: get_layer ($ label, 'layer ');
81. Print_r ($ layeray );
82. ?>