PHP的for循环和foreach循环

PHP中的for循环

<?php

$arr = array("a", "b", "c");

for( $i = 0; $i < count($arr); $i++){
    echo $arr[$i];
};

// count 相当于js中的 length

?>

优化一下

<?php

$arr = array("a", "b", "c", ‘d‘);

$num = count($arr);

for( $i = 0; $i < $num; $i++){
    echo $arr[$i].‘<br>‘;
};

// count 相当于js中的 length

?>

在php中， for循环其实并不常用， 最常用的还是foreach循环

foreach循环

<?php

    $arr = array("a", "b", "c", ‘d‘, ‘e‘);

    foreach($arr as $value){
        echo "{$value}<br>";
    };

?>

foreach的强大之处在于可以输出下标

<?php

    $arr = array("a", "b", "c", ‘d‘, ‘one‘=>‘e‘);

    foreach($arr as $key => $value){
        echo "{$key}---{$value}<br>";
    };

?>

看一个数组转成表格的实例

<?php

    $group = [

        [‘name‘ => ‘zs‘ , ‘age‘ => 20 , ‘sex‘ => ‘男‘ , ‘email‘ => ‘[email protected]‘],
        [‘name‘ => ‘as‘ , ‘age‘ => 17 , ‘sex‘ => ‘女‘ , ‘email‘ => ‘[email protected]‘],
        [‘name‘ => ‘zs‘ , ‘age‘ => 20 , ‘sex‘ => ‘男‘ , ‘email‘ => ‘[email protected]‘],
        [‘name‘ => ‘as‘ , ‘age‘ => 20 , ‘sex‘ => ‘女‘ , ‘email‘ => ‘[email protected]‘],
        [‘name‘ => ‘zs‘ , ‘age‘ => 20 , ‘sex‘ => ‘男‘ , ‘email‘ => ‘[email protected]‘],
        [‘name‘ => ‘as‘ , ‘age‘ => 20 , ‘sex‘ => ‘女‘ , ‘email‘ => ‘[email protected]‘],
        [‘name‘ => ‘zs‘ , ‘age‘ => 20 , ‘sex‘ => ‘男‘ , ‘email‘ => ‘[email protected]‘],
        [‘name‘ => ‘as‘ , ‘age‘ => 20 , ‘sex‘ => ‘女‘ , ‘email‘ => ‘[email protected]‘]

    ];

    echo ‘<table border="1" width="800" align="center">‘;

    echo ‘<caption><h1>数组转表格实例</h1></caption>‘;

    // foreach循环

    foreach($group as $row){

        echo ‘<tr>‘;

        foreach($row as $col){
            echo ‘<td>‘.$col.‘</td>‘;
        };

        echo ‘</tr>‘;
    };

?>