PHP`继续`不按预期工作

Question

我遇到的问题是PHP不能正确处理我的continue。我的代码如下：

$count = -1; 
foreach ($lines as $item){ 
    $count++; 

    if ($item == ""){ 
     continue; // don't process empty items 
    } 
    if ($count > 0){ 
     echo '-not the first line-'; 
    } 

    switch ($item){ 
     case "item1": 
      echo "item 1 found"; 
     break; 
    } 
} 

的if ($count > 0)部分执行无论在哪里continue放在之前，但switch按预期执行。

如果我删除if ($count > 0)，并把它内开关，它按预期执行：

switch ($item){ 
     case "item1": 
      if ($count > 0){ 
       echo '-not the first line-'; // executes as expected 
      } 
      echo "item 1 found"; 
     break; 
    } 

这是正常的吗？谢谢

Answer 1

如果（$ count> 0）部分执行，而不管继续放在它之前的位置，但交换机按预期执行。

您的期望是它不执行？您将$ count设置为“-1”，然后用$ count ++增加它。在我的书中，$ count将是0，它不会大于0，这意味着if条件是真的吗？

编辑：基于我从评论中得到的信息，您没有使用第一行的内容，而您仅使用$ count来跟踪迭代次数？如果是这样;出现以下情况：

<?php 

$lines = array(
    'first', 
    'foo', 
    'bar', 
    'baz', 
    'item1' 
); 

$first = array_shift($lines); // remove it if you don't use it? 
$lines = array_filter($lines); // remove empty lines. 
$count = 0; // set count to 0, although you could just count($lines) as well. 

foreach ($lines as $item){ 
    $count ++; 
    echo '-not the first line-'."\n"; 

    if($item === 'item1') { 
     echo "item 1 found\n"; 
    } 
} 

Answer 2

即使您没有继续阻止，您的第二个示例仍然适用于您。

$count = -1; 
foreach ($lines as $item){ 
    $count++; 

    switch ($item){ 
     case "item1": 
      if ($count > 0){ 
       echo '-not the first line-'; // executes as expected 
      } 
      echo "item 1 found"; 
     break; 
    } 
} 

如果您$item == ""这显然是$item != "item1"所以唯一的情况下也不会被执行。在你的示例代码中，这相当于之前有一个继续。我的猜测是你的$ item不是你想象的那样。试试var_dump($item)吧。

EDIT1：本地测试

<pre><?php 

$lines = array("", "", "John Doe", "", "2011", "", "", "item1"); 

$count = -1; 
foreach ($lines as $item){ 
    $count++; 

    if ($item == ""){ 
     echo "\t(skipping empty item)\n"; 
     continue; // don't process empty items 
    } 
    if ($count > 0){ 
     echo "-not the first line-\n"; 
    } 
    else 
     echo $item." is the first line\n"; 

    switch ($item){ 
     case "item1": 
      echo "item 1 found\n"; 
     break; 
    } 
} 
?> 

将输出

(skipping empty item) 
    (skipping empty item) 
-not the first line- 
    (skipping empty item) 
-not the first line- 
    (skipping empty item) 
    (skipping empty item) 
-not the first line- 
item 1 found 

具有

$lines = array("foobar", "", "John Doe", "", "2011", "", "", "item1"); 

将输出

foobar is the first line 
    (skipping empty item) 
-not the first line- 
    (skipping empty item) 
-not the first line- 
    (skipping empty item) 
    (skipping empty item) 
-not the first line- 
item 1 found 

在continue-statement下面移动$count++;，使其工作。

<pre><?php 

$lines = array("", "", "John Doe", "", "2011", "", "", "item1"); 

$count = -1; 
foreach ($lines as $item){ 

    if ($item == ""){ 
     echo "\t(skipping empty item)\n"; 
     continue; // don't process empty items 
    } 
    $count++; 
    if ($count > 0){ 
     echo "-not the first line-\n"; 
    } 
    else 
     echo $item." is the first line\n"; 

    switch ($item){ 
     case "item1": 
      echo "item 1 found\n"; 
     break; 
    } 
} 

?> 

输出

(skipping empty item) 
    (skipping empty item) 
John Doe is the first line 
    (skipping empty item) 
-not the first line- 
    (skipping empty item) 
    (skipping empty item) 
-not the first line- 
item 1 found