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PHP array_merge合并拆分两个数组

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Jun 13, 2016 am 10:15 AM

array merge php 函数合并和对拆分数组比较的运算符

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。

代码如下

复制代码

$arr1=array("a","b","c");
$arr2=array("c","d","e");

$myarray=array_merge($arr1,$arr2);
print_r($myarray);

$myarray=array_unique($myarray);

print_r($myarray);
?>

例

代码如下	复制代码
$array1=array(1, 2);//数组1 $array2=array(2, 3);//数组2 $array3=array_merge($array1, $array2);//合并数组; $array3=array_unique($array3);//移除数组中重复的值 ?>

例子

代码如下

复制代码

echo "rn第一种情况rn";
$a=array(1,2,3,4,5,6);
$b=array(7,8,9);

$c=array_merge ($a,$b);
print_r($c);
$c=$a+$b;
print_r($c);
$c=$b+$a;
print_r($c);

echo "rn第二种情况rn";
$a=array('a','b','c','d','e','f');
$b=array('a','x','y');

$c=array_merge ($a,$b);
print_r($c);
$c=$a+$b;
print_r($c);
$c=$b+$a;
print_r($c);

echo "rn第三种情况rn";

$a=array(
1=>'a',
2=>'b',
3=>'c',
4=>'d',
5=>'e',
6=>'f');
$b=array(
1=>'a',
7=>'x',
8=>'y');

$c=array_merge ($a,$b);
print_r($c);
$c=$a+$b;
print_r($c);
$c=$b+$a;
print_r($c);
?>

结果如下：

第一种情况
Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
    [5] => 6
    [6] => 7
    [7] => 8
    [8] => 9
)
Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
    [5] => 6
)
Array
(
    [0] => 7
    [1] => 8
    [2] => 9
    [3] => 4
    [4] => 5
    [5] => 6
)

第二种情况
Array
(
    [0] => a
    [1] => b
    [2] => c
    [3] => d
    [4] => e
    [5] => f
    [6] => a
    [7] => x
    [8] => y
)
Array
(
    [0] => a
    [1] => b
    [2] => c
    [3] => d
    [4] => e
    [5] => f
)
Array
(
    [0] => a
    [1] => x
    [2] => y
    [3] => d
    [4] => e
    [5] => f
)

第三种情况
Array
(
    [0] => a
    [1] => b
    [2] => c
    [3] => d
    [4] => e
    [5] => f
    [6] => a
    [7] => x
    [8] => y
)
Array
(
    [1] => a
    [2] => b
    [3] => c
    [4] => d
    [5] => e
    [6] => f
    [7] => x
    [8] => y
)
Array
(
    [1] => a
    [7] => x
    [8] => y
    [2] => b
    [3] => c
    [4] => d
    [5] => e
    [6] => f
)

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

代码如下

复制代码

$fruits = array("Apple", "Banana", "Orange", "Pear", "Grape", "Lemon", "Watermelon");
$subset = array_slice($fruits, 3);
print_r($subset);

// output
// Array ( [0] => Pear [1] => Grape [2] => Lemon [3] => Watermelon )
?>

然后我们使用下负长度：

Php代码

代码如下

复制代码

$fruits = array("Apple", "Banana", "Orange", "Pear", "Grape", "Lemon", "Watermelon");
$subset = array_slice($fruits, 2, -2);
print_r($subset);

// output
// Array ( [0] => Orange [1] => Pear [2] => Grape )
?>

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