PHP中的for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>';
    };
?>