对数组的array_merge函数和+运算符比较迷惑,写了个小程序比较下发现了他们的不同. 特别是+运算符,他的意思是,将右边的数组单元（去重复）追加到左边数组的后面.

实例代码如下:

1. <?php
2. $arr1=array("a","b","c");
3. $arr2=array("c","d","e");
4. $myarray=array_merge($arr1,$arr2);
5. print_r($myarray);
6. $myarray=array_unique($myarray);
7. print_r($myarray);
8. ?>

实例代码如下:

1. <?php
2. $array1=array(1, 2);//数组1
3. $array2=array(2, 3);//数组2
4. $array3=array_merge($array1, $array2);//合并数组;
5. $array3=array_unique($array3);//移除数组中重复的值
6. ?>

实例代码如下:

1. <?php
2. echo "rn第一种情况rn";
3. $a=array(1,2,3,4,5,6);
4. $b=array(7,8,9);
5. $c=array_merge ($a,$b);
6. print_r($c);
7. $c=$a+$b;
8. print_r($c);
9. $c=$b+$a;
10. print_r($c);
11. echo "rn第二种情况rn";
12. $a=array('a','b','c','d','e','f');
13. $b=array('a','x','y');
14. $c=array_merge ($a,$b);
15. print_r($c);
16. $c=$a+$b;
17. print_r($c);
18. $c=$b+$a;
19. print_r($c);
20. echo "rn第三种情况rn";
21. $a=array(
22. 1=>'a',
23. 2=>'b',
24. 3=>'c',
25. 4=>'d',
26. 5=>'e',
27. 6=>'f');
28. $b=array(
29. 1=>'a',
30. 7=>'x',
31. 8=>'y');
32. $c=array_merge ($a,$b);
33. print_r($c);
34. $c=$a+$b;
35. print_r($c);
36. $c=$b+$a;
37. print_r($c);
38. ?>

结果如下:

1. 第一种情况
2. Array
3. (
4. [0] => 1
5. [1] => 2
6. [2] => 3
7. [3] => 4
8. [4] => 5
9. [5] => 6
10. [6] => 7
11. [7] => 8
12. [8] => 9
13. )
14. Array
15. (
16. [0] => 1
17. [1] => 2
18. [2] => 3
19. [3] => 4
20. [4] => 5
21. [5] => 6
22. )
23. Array
24. (
25. [0] => 7
26. [1] => 8
27. [2] => 9
28. [3] => 4
29. [4] => 5
30. [5] => 6
31. )
32. 第二种情况
33. Array
34. (
35. [0] => a
36. [1] => b
37. [2] => c
38. [3] => d
39. [4] => e
40. [5] => f
41. [6] => a
42. [7] => x
43. [8] => y
44. )
45. Array
46. (
47. [0] => a
48. [1] => b
49. [2] => c
50. [3] => d
51. [4] => e
52. [5] => f
53. )
54. Array
55. (
56. [0] => a
57. [1] => x
58. [2] => y
59. [3] => d
60. [4] => e
61. [5] => f
62. )
63. 第三种情况
64. Array
65. (
66. [0] => a
67. [1] => b
68. [2] => c
69. [3] => d
70. [4] => e
71. [5] => f
72. [6] => a
73. [7] => x
74. [8] => y
75. )
76. Array
77. (
78. [1] => a
79. [2] => b
80. [3] => c
81. [4] => d
82. [5] => e
83. [6] => f
84. [7] => x
85. [8] => y
86. )
87. Array
88. (
89. [1] => a
90. [7] => x
91. [8] => y
92. [2] => b
93. [3] => c
94. [4] => d
95. [5] => e
96. [6] => f
97. )

拆分数组 array_slice()

array_slice()函数将返回数组中的一部分,从键offset开始,到offset+length位置结束.其形式:

Php代码

1.array array_slice (array array, int offset[,int length])

array array_slice (array array, int offset[,int length])

offset 为正值时,拆分将从距数组开头的offset 位置开始；如果offset 为负值,则拆分从距数组末尾的offset 位置开始.如果省略了可选参数length,则拆分将从offset 开始,一直到数组的最后一个元素.如果给出了length 且为正数,则会在距数组开头的offset+length 位置结束.相反,如果给出了length且为负数,则在距数组开头的count(input_array)-|length|位置结束.考虑一个例子:

Php代码

实例代码如下:

1. <?php
2. $fruits = array("Apple", "Banana", "Orange", "Pear", "Grape", "Lemon", "Watermelon");
3. $subset = array_slice($fruits, 3);
4. print_r($subset);
5. // output
6. // Array ( [0] => Pear [1] => Grape [2] => Lemon [3] => Watermelon )
7. ?>

然后我们使用下负长度:

Php代码

实例代码如下:

1. <?php
2. $fruits = array("Apple", "Banana", "Orange", "Pear", "Grape", "Lemon", "Watermelon");
3. $subset = array_slice($fruits, 2, -2);
4. print_r($subset);
5. // output
6. // Array ( [0] => Orange [1] => Pear [2] => Grape )
7. ?>