PHP 数组
Indexed and associative arrays, CRUD operations, and common array functions.
Key PointsA PHP array is an ordered key-value map — it doubles as list, dictionary and stack.
两种数组
PHP has one array type: an ordered hash table. Integer keys make it indexed, string keys make it associative — and you can mix them.
PHP
<?php
$fruits = ["apple", "banana", "cherry"];
echo count($fruits), "\n";
echo $fruits[1], "\n";
$user = ["name" => "Tom", "age" => 18];
echo $user["name"], "\n";
// 混合键
$mix = [0 => "a", "k" => "b", 5 => "c"];
print_r($mix);Output
3
banana
Tom
Array
(
[0] => a
[k] => b
[5] => c
)增删改
PHP
<?php
$fruits = ["apple", "banana", "cherry"];
$user = ["name" => "Tom", "age" => 18];
$user["city"] = "上海";
print_r($user);
array_push($fruits, "date");
array_unshift($fruits, "zero");
print_r($fruits);
unset($fruits[0]);
print_r($fruits);Output
Array
(
[name] => Tom
[age] => 18
[city] => 上海
)
Array
(
[0] => zero
[1] => apple
[2] => banana
[3] => cherry
[4] => date
)
Array
(
[1] => apple
[2] => banana
[3] => cherry
[4] => date
)unset() removes the element but does not reindex. After deleting key 0 the keys start at 1, breaking index-based for loops. Use array_values() to reindex.PHP
<?php
$arr = [1, 2, 3];
unset($arr[1]);
print_r($arr);
print_r(array_values($arr));
echo implode(",", $arr), "\n";Output
Array
(
[0] => 1
[2] => 3
)
Array
(
[0] => 1
[1] => 3
)
1,3常用函数
| Function | Purpose | Example |
|---|---|---|
| count | 元素个数 | count([1,2,3]) → 3 |
| array_keys | 所有键 | array_keys(["a"=>1]) → ["a"] |
| array_values | 所有值并重排键 | array_values([5=>1]) → [0=>1] |
| array_merge | 合并（字符串键覆盖） | array_merge([1],[2]) → [1,2] |
| array_slice | 截取一段 | array_slice([1,2,3],1) → [2,3] |
| array_splice | 删除并替换 | 会改动原数组 |
| array_search | 查值返回键 | 找不到返回 false |
| in_array | 判断值是否存在 | 第三个参数 true 严格比 |
| array_sum | 求和 | array_sum([1,2,3]) → 6 |
| array_unique | 去重（保留首个键） | 键会留下空洞 |
| array_filter | 按回调过滤 | 保留原键 |
| array_map | 逐个映射 | 重新索引 |
| array_column | 取二维数组某列 | 报表场景常用 |
PHP
<?php
print_r(array_merge([1, 2], [3, 4]));
[$a, $b] = [10, 20];
echo $a + $b, "\n";
$spread = [...[1, 2], ...[3, 4]];
echo implode(",", $spread), "\n";
$rows = [
["id" => 1, "name" => "Tom"],
["id" => 2, "name" => "Amy"],
];
print_r(array_column($rows, "name"));
echo array_sum([1, 2, 3, 4]), "\n";Output
Array
(
[0] => 1
[1] => 2
[2] => 3
[3] => 4
)
30
1,2,3,4
Array
(
[0] => Tom
[1] => Amy
)
10解构与展开
list() / [] destructuring works positionally or by key, including nested arrays.
PHP
<?php
[$a, , $c] = [1, 2, 3]; // 跳过第二个
echo "$a $c\n";
["name" => $n, "age" => $age] = ["name" => "Tom", "age" => 18];
echo "$n $age\n";
[[$x, $y], [$p, $q]] = [[1, 2], [3, 4]];
echo $x + $y + $p + $q, "\n";
function pair(): array {
return [1, 2];
}
[$first, $second] = pair();
echo $first + $second, "\n";Output
1 3
Tom 18
10
3什么时候用数组、什么时候用对象
- Temporary collections, config, multiple return values —— arrays suffice
- Data with behaviour —— use a class, not a bag of agreed keys
- External input —— arrays map naturally to JSON
两种数组
PHP 只有一种数组类型：有序哈希表。键是整数就叫索引数组，键是字符串就叫关联数组，两者可以混用。
PHP
<?php
$fruits = ["apple", "banana", "cherry"];
echo count($fruits), "\n";
echo $fruits[1], "\n";
$user = ["name" => "Tom", "age" => 18];
echo $user["name"], "\n";
// 混合键
$mix = [0 => "a", "k" => "b", 5 => "c"];
print_r($mix);Output
3
banana
Tom
Array
(
[0] => a
[k] => b
[5] => c
)增删改
PHP
<?php
$fruits = ["apple", "banana", "cherry"];
$user = ["name" => "Tom", "age" => 18];
$user["city"] = "上海";
print_r($user);
array_push($fruits, "date");
array_unshift($fruits, "zero");
print_r($fruits);
unset($fruits[0]);
print_r($fruits);Output
Array
(
[name] => Tom
[age] => 18
[city] => 上海
)
Array
(
[0] => zero
[1] => apple
[2] => banana
[3] => cherry
[4] => date
)
Array
(
[1] => apple
[2] => banana
[3] => cherry
[4] => date
)unset() 只删元素，不会重排索引。上面删掉 0 之后键从 1 开始，for ($i = 0; $i < count($arr); $i++) 就会取不到第一个元素。要重排用 array_values()。PHP
<?php
$arr = [1, 2, 3];
unset($arr[1]);
print_r($arr);
print_r(array_values($arr));
echo implode(",", $arr), "\n";Output
Array
(
[0] => 1
[2] => 3
)
Array
(
[0] => 1
[1] => 3
)
1,3常用函数
| 函数 | 作用 | 示例 |
|---|---|---|
| count | 元素个数 | count([1,2,3]) → 3 |
| array_keys | 所有键 | array_keys(["a"=>1]) → ["a"] |
| array_values | 所有值并重排键 | array_values([5=>1]) → [0=>1] |
| array_merge | 合并（字符串键覆盖） | array_merge([1],[2]) → [1,2] |
| array_slice | 截取一段 | array_slice([1,2,3],1) → [2,3] |
| array_splice | 删除并替换 | 会改动原数组 |
| array_search | 查值返回键 | 找不到返回 false |
| in_array | 判断值是否存在 | 第三个参数 true 严格比 |
| array_sum | 求和 | array_sum([1,2,3]) → 6 |
| array_unique | 去重（保留首个键） | 键会留下空洞 |
| array_filter | 按回调过滤 | 保留原键 |
| array_map | 逐个映射 | 重新索引 |
| array_column | 取二维数组某列 | 报表场景常用 |
PHP
<?php
print_r(array_merge([1, 2], [3, 4]));
[$a, $b] = [10, 20];
echo $a + $b, "\n";
$spread = [...[1, 2], ...[3, 4]];
echo implode(",", $spread), "\n";
$rows = [
["id" => 1, "name" => "Tom"],
["id" => 2, "name" => "Amy"],
];
print_r(array_column($rows, "name"));
echo array_sum([1, 2, 3, 4]), "\n";Output
Array
(
[0] => 1
[1] => 2
[2] => 3
[3] => 4
)
30
1,2,3,4
Array
(
[0] => Tom
[1] => Amy
)
10解构与展开
list() / [] 解构可以按位置或按键取值，嵌套数组也支持。
PHP
<?php
[$a, , $c] = [1, 2, 3]; // 跳过第二个
echo "$a $c\n";
["name" => $n, "age" => $age] = ["name" => "Tom", "age" => 18];
echo "$n $age\n";
[[$x, $y], [$p, $q]] = [[1, 2], [3, 4]];
echo $x + $y + $p + $q, "\n";
function pair(): array {
return [1, 2];
}
[$first, $second] = pair();
echo $first + $second, "\n";Output
1 3
Tom 18
10
3数组还是对象
- 临时集合、配置、函数返回多值 —— 数组够用
- 有行为的数据 —— 用类，别用一堆约定好的键名
- 外部输入 —— 数组天然对应 JSON，解码后直接可用