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php实现foreach遍历

2026-02-15 15:19:51PHP

使用 foreach 遍历数组

在 PHP 中，foreach 是遍历数组的常用方法，适用于索引数组和关联数组。

$fruits = ["apple", "banana", "orange"];

foreach ($fruits as $fruit) {
    echo $fruit . "\n";
}

输出结果：

apple
banana
orange

遍历关联数组

对于关联数组，可以同时获取键和值：

$person = [
    "name" => "John",
    "age" => 30,
    "city" => "New York"
];

foreach ($person as $key => $value) {
    echo "$key: $value\n";
}

输出结果：

name: John
age: 30
city: New York

遍历多维数组

对于多维数组，可以使用嵌套的 foreach 循环：

$users = [
    ["id" => 1, "name" => "Alice"],
    ["id" => 2, "name" => "Bob"],
    ["id" => 3, "name" => "Charlie"]
];

foreach ($users as $user) {
    foreach ($user as $key => $value) {
        echo "$key: $value ";
    }
    echo "\n";
}

输出结果：

id: 1 name: Alice
id: 2 name: Bob
id: 3 name: Charlie

引用方式遍历

如果需要修改原数组的值，可以使用引用方式：

$numbers = [1, 2, 3, 4];

foreach ($numbers as &$number) {
    $number *= 2;
}

print_r($numbers);

输出结果：

Array
(
    [0] => 2
    [1] => 4
    [2] => 6
    [3] => 8
)

遍历对象

foreach 也可以遍历实现了 Iterator 接口的对象：

class MyIterator implements Iterator {
    private $position = 0;
    private $array = ['first', 'second', 'third'];

    public function rewind() {
        $this->position = 0;
    }

    public function current() {
        return $this->array[$this->position];
    }

    public function key() {
        return $this->position;
    }

    public function next() {
        ++$this->position;
    }

    public function valid() {
        return isset($this->array[$this->position]);
    }
}

$it = new MyIterator;

foreach($it as $key => $value) {
    echo "$key: $value\n";
}

输出结果：