这篇笔记介绍php中的代码控制流程的语法。
if...else if...else...
结构示例代码:
<?php
$a = 1;
$b = 2;
if ($a == $b) {
echo "a=b";
} else if ($a > $b) {
echo "a>b";
} else {
echo "a<b";
}
?>
switch...case...
结构示例代码:
<?php
$num = rand(1,50);//获取1至50的随机数
$info = "";//提示信息
switch($num){
case 1:
$info = "恭喜你!中了一等奖!";
break;
case 2:
$info = "恭喜你!中了二等奖!";
break;
case 3:
$info = "恭喜你!中了三等奖!";
break;
default:
$info = "很遗憾!你没有中奖!";
}
echo $info; //输出是否中奖
?>
注意:和其它编程语言的switch一样,别忘了break
。
while
结构示例代码:
<?php
$count = 0;
while ($count < 5) {
$count++;
}
echo $count;
?>
do...while
结构示例代码:
<?php
$count = 0;
do {
$count++;
} while ($count < 5);
echo $count;
?>
for
结构示例代码:
<?php
$sum = 0;
for ($i = 1; $i <= 100; $i++) {
$sum += $i;
}
echo $sum;
?>
foreach
结构示例代码(遍历数组):
<?php
$students = array(
'2010' => '令狐冲',
'2011' => '林平之',
'2012' => '曲洋',
'2013' => '任盈盈',
'2014' => '向问天',
'2015' => '任我行',
'2016' => '冲虚',
'2017' => '方正',
'2018' => '岳不群',
'2019' => '宁中则',
);
//只输出数组的值
foreach ($students as $v) {
echo $v;
echo "<br />";
}
//输出数组的下标和值
foreach ($students as $n => $v) {
echo $n . "=>" . $v;
echo "<br />";
}
?>