Detailed example of the usage of foreach in php

1. What is foreach?

foreach is a grammatical structure of PHP. It is actually a tool (tool: a tool used when working). In the process of program development, in order to achieve program effects, use Arrived foreach.

2. How to use?

Official:

foreach (array_expression as $value) statement foreach (array_expression as $key => $value) statement

Example:

$arr = array(1,2,3,4);//定义数组 foreach ($arr as &$value) { $value = $value*2;//循环遍历并修改数组中的值 } echo "
"; print_r($arr);//打印输出最终结果
      
Result: (&$value is a reference assignment)

      
　　Array 　　( 　　[0] => 2 　　 [1] => 4 　　 [2] => 6 　　 [3] => 8 　　)
      
Example:
      
$a = array( "one" => 1, "two" => 2, "three" => 3, "seventeen" => 17 ); foreach ($a as $k => $v) { echo "
"; echo "[$k] => $v\n"; }
      
Result:

      
[one] => 1 [two] => 2 [three] => 3 [seventeen] => 17
      
Explanation: k actually refers to key, v actually refers to value
Summary: foreach is frequently used in PHP projects, especially when processing Array time!
      
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