PHP`繼續`不按預期工作

Question

我遇到的問題是PHP不能正確處理我的continue。我的代碼如下：

$count = -1; 
foreach ($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)部分執行無論在哪裏continue放在之前，但switch按預期執行。

如果我刪除if ($count > 0)，並把它內開關，它按預期執行：

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

這是正常的嗎？謝謝

Answer 1

如果（$ count> 0）部分執行，而不管繼續放在它之前的位置，但交換機按預期執行。

您的期望是它不執行？您將$ count設置爲「-1」，然後用$ count ++增加它。在我的書中，$ count將是0，它不會大於0，這意味着if條件是真的嗎？

編輯：基於我從評論中得到的信息，您沒有使用第一行的內容，而您僅使用$ count來跟蹤迭代次數？如果是這樣;出現以下情況：

<?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

即使您沒有繼續阻止，您的第二個示例仍然適用於您。

$count = -1; 
foreach ($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$item == ""這顯然是$item != "item1"所以唯一的情況下也不會被執行。在你的示例代碼中，這相當於之前有一個繼續。我的猜測是你的$ item不是你想象的那樣。試試var_dump($item)吧。

EDIT1：本地測試

<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; 
    } 
} 
?> 

將輸出

(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"); 

將輸出

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下面移動$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; 
    } 
} 

?> 

輸出

(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