freeCodeCamp/guide/chinese/php/loop/index.md

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!"