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作业效果
<meta charset="UTF-8">
<!DOCTYPE html>
<html lang="en">
<head>
<title>For(), while(),foreach(),实现索引数组，关联数组的遍历</title>
<style type="text/css">
h3,h4 {
text-align: center;
}
.box1 {
text-align: center;
}
.box2 {
text-align: center;
}
.box3 {
text-align: center;
}
table {
margin: auto;
}
caption {
font-size: 2em;
color: red
}
th {
color: green;
}
td {
color:fuchsia;
font-size: 1.2em;
}
</style>
</head>
<body>
<?php
echo '<h3 style="color:green"> For(), while(),foreach(),实现索引数组，关联数组的遍历</h3><hr color="green">';
/*
* 数组遍历
* 1. foreach($arr as $key => $value) {}
* 2. 原理:将数组$arr按键值对方式依次取出到$key=>$value中,逐个处理,类似于回调
* 3. 如果只对值处理,可以省略$key: foreach($arr as $value) {}
* 4. 特殊适合关联数组,当然也适用于索引数组
*/
$color = ['red'=>'红', 'orenge'=>'橙', 'yellow'=>'黄', 'green'=>'绿', 'cyan'=>'青', 'blue'=>'蓝' ,'purple'=>'紫'];
echo '<div class=box1>';
///////用for循环来实现关联数组的遍历////////
///
///
echo '<h3 style="color:green">用for来实现循环遍历</h3>';
for ($i=0; $i<count($color); $i++) {
echo key($color),'(',current($color),')','<br>';
next($color);
}
echo '</div>';
echo '<hr color="red">';
//////////用while循环来实现//////////////////
echo '<div class=box2>';
echo '<h3 style="color:green">用while来实现循环遍历</h3>';
reset($color);
$i = 0;
while ($i<count($color)) {
echo key($color),'=>',current($color),'<br>';
next($color);
$i++;
}
echo '</div>';
echo '<hr color="red">';
/////////foreach($arr as $key=>$value):数组专用的遍历语法结构///////
echo '<div class=box3>';
echo '<h3 style="color:green">用foreach($arr as $key=>$value):数组专用的遍历语法结构</h3>';
echo '<h4>彩虹的颜色</h4>';
echo '<ul>';
foreach ($color as $key => $value) {
echo '<li>'.$key.':'.$value.'</li>';
}
echo '</ul>';
echo '</div>';
echo '<hr color="red">';
///////////如果只对值感兴趣///////
echo '<table border="1" cellpadding="3" cellspacing="0" width="300">';
echo '<caption>彩虹颜色</caption>';
echo'<tr>';
foreach ($color as $key => $value) {
echo '<th align="center">'.$key.'</th>';
}
echo '</tr>';
echo '<tr>';
foreach ($color as $key => $value) {
echo '<td align="center">'.$value.'</td>';
}
echo '</tr>';
echo '</table>';
echo '<hr color="red">';
?>
</body>
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