在数组合并的时候能够使用两个函数 “+”和“array_merge()”
PHP中两个数组合并可以使用+或者array_merge，但之间还是有区别的，而且这些区别如果了解不清楚项目中会要命的！
主要区别是两个或者多个数组中如果出现相同键名，键名分为字符串或者数字，需要注意
1）键名为数字时，array_merge()后面的值将不会覆盖原来的值，而是附加到后面，但＋合并数组则会把最先出现的值作为最终结果返回，而把后面的数组拥有相同键名的那些值“抛弃”掉（不是覆盖）
2）键名为字符串时，array_merge()此时会覆盖掉前面相同键名的值，但＋仍然把最先出现的值作为最终结果返回，而把后面的数组拥有相同键名的那些值“抛弃”掉（不是覆盖）。
需要注意的是数组键形式 ‘数字‘ 等价于 数字
01 |
$a = array(‘a‘, ‘b‘); |
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$b = array(‘c‘, ‘d‘); |
03 |
$c = $a + $b; |
04 |
var_dump($a); |
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var_dump(array_merge($a, $b)); |
06 |
07 |
//输出： |
08 |
09 |
array |
10 |
0 => string ‘a‘ (length=1) |
11 |
1 => string ‘b‘ (length=1) |
12 |
13 |
array |
14 |
0 => string ‘a‘ (length=1) |
15 |
1 => string ‘b‘ (length=1) |
16 |
2 => string ‘c‘ (length=1) |
17 |
3 => string ‘d‘ (length=1) |
18 |
19 |
++++++++++++++++++++++++++++++++++++++++++ |
20 |
|
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$a = array( |
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0 => ‘a‘, |
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1 => ‘b‘ |
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); |
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$b = array( |
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0 => ‘c‘, |
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1 => ‘b‘ |
28 |
); |
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$c = $a + $b; |
30 |
var_dump($c); |
31 |
var_dump(array_merge($a, $b)); |
32 |
33 |
//输出： |
34 |
35 |
array |
36 |
0 => string ‘a‘ (length=1) |
37 |
1 => string ‘b‘ (length=1) |
38 |
39 |
array |
40 |
0 => string ‘a‘ (length=1) |
41 |
1 => string ‘b‘ (length=1) |
42 |
2 => string ‘c‘ (length=1) |
43 |
3 => string ‘b‘ (length=1) |
44 |
45 |
++++++++++++++++++++++++++++++++++++++++++ |
46 |
47 |
$a = array(‘a‘, ‘b‘); |
48 |
$b = array( |
49 |
‘0‘ => ‘c‘, |
50 |
1 => ‘b‘ |
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); |
52 |
$c = $a + $b; |
53 |
var_dump($c); |
54 |
var_dump(array_merge($a, $b)); |
55 |
56 |
//输出： |
57 |
array |
58 |
0 => string ‘a‘ (length=1) |
59 |
1 => string ‘b‘ (length=1) |
60 |
61 |
array |
62 |
0 => string ‘a‘ (length=1) |
63 |
1 => string ‘b‘ (length=1) |
64 |
2 => string ‘c‘ (length=1) |
65 |
3 => string ‘b‘ (length=1) |
66 |
67 |
++++++++++++++++++++++++++++++++++++++++++ |
68 |
69 |
$a = array( |
70 |
0 => ‘a‘, |
71 |
1 => ‘b‘ |
72 |
); |
73 |
$b = array( |
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‘0‘ => ‘c‘, |
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‘1‘ => ‘b‘ |
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); |
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$c = $a + $b; |
78 |
var_dump($c); |
79 |
var_dump(array_merge($a, $b)); |
80 |
81 |
输出： |
82 |
83 |
array |
84 |
0 => string ‘a‘ (length=1) |
85 |
1 => string ‘b‘ (length=1) |
86 |
87 |
array |
88 |
0 => string ‘a‘ (length=1) |
89 |
1 => string ‘b‘ (length=1) |
90 |
2 => string ‘c‘ (length=1) |
91 |
3 => string ‘b‘ (length=1) |
对多个数组合并去重技巧
1 |
$a = array(‘1001‘,‘1002‘); |
2 |
$b = array(‘1002‘,‘1003‘,‘1004‘); |
3 |
$c = array(‘1003‘,‘1004‘,‘1005‘); |
4 |
$d = count(array_flip($a) + array_flip($b) + array_flip($c)); |
时间： 2024-10-09 21:16:36