How to write two-dimensional array in PHP

In PHP's two-dimensional array, each element of the array is an array, and these arrays all have the same key. The following is how to write a two-dimensional array in PHP and some examples:

1. Define a two-dimensional array

You can use the array() function to define a two-dimensional array. Here are some examples of defining two-dimensional arrays:

// 定义一个空数组
$array = array();

// 定义一个二维数组
$array = array(
    array(1, 2, 3),
    array(4, 5, 6),
    array(7, 8, 9)
);

// 定义一个关联数组
$array = array(
    'row1' => array('id'=>1, 'name'=>'Tom', 'age'=>18),
    'row2' => array('id'=>2, 'name'=>'Jerry', 'age'=>20),
    'row3' => array('id'=>3, 'name'=>'Mike', 'age'=>22),
);

2. Accessing two-dimensional array elements

When accessing elements in a two-dimensional array, two keys need to be specified, That is, the bonds of the first and second dimensions. Here are some examples of accessing elements of a two-dimensional array:

// 访问二维数组中的元素
echo $array[0][0]; // 输出 1
echo $array[1][1]; // 输出 5
echo $array[2][2]; // 输出 9

// 访问关联数组中的元素
echo $array['row1']['name']; // 输出 Tom
echo $array['row2']['age']; // 输出 20
echo $array['row3']['id']; // 输出 3

3. Traversing a two-dimensional array

You can use a for loop or a foreach loop to traverse a two-dimensional array. The following are some examples of traversing two-dimensional arrays:

// 使用 for 循环遍历二维数组
for ($i = 0; $i < count($array); $i++) {
    for ($j = 0; $j < count($array[$i]); $j++) {
        echo $array[$i][$j] . &#39; &#39;;
    }
    echo &#39;<br>';
}

// 使用 foreach 循环遍历关联数组
foreach ($array as $key => $value) {
    echo $key . ': ';
    foreach ($value as $k => $v) {
        echo $k . '=' . $v . ' ';
    }
    echo '<br>';
}

The above is the writing method and examples of two-dimensional arrays in PHP. I hope it will be helpful to you.

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