Detailed explanation of 'foreach' loop statement examples of PHP loop control statements

This chapter introduces a special loop statement in PHP, the "foreach" loop statement.

What is the foreach loop used for?

In PHP, the foreach loop statement is specially used to loop through arrays. For arrays, you can check this articlehttp://www.php.cn/php-weizijiaocheng- 360217.html

foreach loop syntax format

There are two ways to write the foreach loop syntax. The first way is as follows

foreach (array_variable as val) 
    statement;

array_variable represents an array variable. During each loop execution, the value of each element will be temporarily assigned to the variable val. The value of val obtained by the statement statement is different each time.

Two ways of writing

foreach (array_variable as key => val) 
    statement;

key represents the subscript of the array, and val represents the value of the array. So for a numeric subscript array, the value of key in each loop is the number that starts from 0 and grows.

foreach loop instance

<?php
header("Content-type:text/html;charset=utf-8");    //设置编码

$a=Array("苹果","橘子","香蕉");

foreach($a as $value){

    echo $value."<br/>";
}


?>

Code running result:

Detailed explanation of the example:

We said at the beginning that the "foreach" loop is specially used to loop arrays. So, we first define an array $a. There are three values ​​in the array. They are "apple", "orange", and "banana", and then use the foreach loop statement to loop through the array and output the values ​​in the array.

The above example is the first way of writing using foreach loop. At this time, if you want to get the $key of the array, you need to use our second way of writing, The code is as follows:

<?php
header("Content-type:text/html;charset=utf-8");    //设置编码

$a = array(
    "one" => 1,
    "two" => 2,
    "three" => 3,
    "seventeen" => 17
);
foreach ($a as $key => $val) {
    echo $key .":".$val."<br/>";
}

?>

Code running results:

The two examples above are simple applications of the two writing methods of foreach loop.

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