php adds key-value pairs to array

php method to add key-value pairs to an array: First create a PHP sample file; then use the foreach statement to add key-value pairs to the array, with statements such as "foreach ($a as &$item) { $item['b'] = "value";}".

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Use foreach to add key-value pairs to the array in php

In PHP, the frequency of using foreach to traverse arrays is very high, and its performance is higher than the combination of list() and each() to traverse arrays:

When traversing the first level of a two-digit array array, and want to add a new key-value pair to the second array. For example, I have a two-dimensional array structure like this

$a = array(
     array(
        'a' => "first"
      ),
     array(
        'a' => "second"
      )
 );

This is my plan to add a key-value pair to each array in the second layer

 'b' => "value"

If foreach is used at this time

foreach ($a as $item) {
        $item['b'] = "value";
    }

The result obtained is the same as the original array, and the key-value pair 'b' is not added => "value"

only We need to make some modifications to the above code to achieve our needs, that is, add an address character & before $item, as follows

foreach ($a as &$item) {
        $item['b'] = "value";
    }

The array obtained in this way is the content we want .

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