2.5 KiB
2.5 KiB
title | localeTitle |
---|---|
Loop | 环 |
PHP循环
当您需要多次重复相同的任务时,您可以使用循环而不是一遍又一遍地添加相同的代码。 在PHP中有以下循环语句:
- for - 循环遍历具有特定次数的代码块。
- while - 如果条件为真,则循环遍历代码块。
- do ... while - 循环遍历代码块1并在条件为真时继续循环。
- foreach - 循环遍历数组中每个值的代码块。
在循环中使用break
可以停止循环执行。
对于循环
循环遍历具有特定次数的代码块。
句法
for (init counter; condition; counter increment or decrement)
{
// Code to be executed
}
例
<?php
for($index = 0; $index < 5; $index ++)
{
echo "Current loop counter ".$index.".\n";
}
?>
产量
> Current loop counter 0.
> Current loop counter 1.
> Current loop counter 2.
> Current loop counter 3.
> Current loop counter 4.
循环
如果条件为真,则循环遍历代码块。
句法
while (condition)
{
// Code to be executed
}
例
<?php
$index = 10;
while ($index >= 0)
{
echo "The index is ".$index.".\n";
$index--;
}
?>
产量
> The index is 10.
> The index is 9.
> The index is 8.
> The index is 7.
> The index is 6.
> The index is 5.
> The index is 4.
> The index is 3.
> The index is 2.
> The index is 1.
> The index is 0.
做......循环
循环遍历代码块1并在条件为真时继续循环。
句法
do
{
// Code to be executed
}
while (condition);
例
<?php
$index = 3;
do
{
// execute this at least 1 time
echo "Index: ".$index.".\n";
$index --;
}
while ($index > 0);
?>
产量
> Index: 3.
> Index: 2.
> Index: 1.
Foreach循环
循环遍历数组中每个值的代码块。
句法
foreach ($array as $value)
{
// Code to be executed
}
例
<?php
$array = ["Ali", "Ah Kao", "Muthu", "Gwen", "Lucida", "Cecily", "Arthur", "Flora"];
foreach ($array as $name)
{
echo "Hi, my name is ".$name.".\n";
if ($name == "Cecily")
{
echo "\"Hello, ".$name."!\"";
// stop the loop if name is Cecily
break;
}
}
?>
产量
> Hi, my name is Ali.
> Hi, my name is Ah Kao.
> Hi, my name is Muthu.
> Hi, my name is Gwen.
> Hi, my name is Lucida.
> Hi, my name is Cecily.
> "Hello, Cecily!"