PHP一直告訴我值是空的

Question

我已經在我的PHP腳本中設置了它，如果一個值爲空，就這樣說。我一直在控制檯上收到一條消息，說這個值是空的，但我似乎無法弄清楚爲什麼，因爲它看起來對我有價值。

這裏是PHP

$percentageOfMessages = $_POST["percentageOfMessages"]; 
$RemoveDeletedAccounts = $_POST["RemoveDeletedAccounts"]; 
$RemoveNoReply = $_POST["RemoveNoReply"]; 
$RemoveNoResponse = $_POST["RemoveNoResponse"]; 
$mintchPercent = $_POST["mintchPercent"]; 
$minDistance = $_POST["minDistance"]; 
$maxDistance = $_POST["maxDistance"]; 

$blacklistUsernames = $_POST["blacklistUsernames"]; 
$pickText = $_POST["pickText"]; 
$userEmail = $_POST["userEmail"]; 

//$captcha = $_POST["captcha"]; 
//$num1 = $_POST["num1"]; 
//$num2 = $_POST["num2"]; 


if (empty($percentageOfMessages)) { 
    echo "percentageOfMessages"; 

}elseif (empty($mintchPercent)) { 
    echo "mintchPercent"; 

}elseif (empty($minDistance)) { 
    echo "minDistance"; 

}elseif (empty($maxDistance)) { 
    echo "maxDistance"; 

}elseif (empty($pickText)) { 
    echo "pickText"; 

}elseif (empty($userEmail)) { 
    echo "userEmail"; 

}else { 

這裏是JavaScript/jQuery的，涉及minDistance纔會

$('#minDistance').keyup(function() { 
     if (this.value != this.value.replace(/[^0-9\.]/g, '')) { 
      this.value = this.value.replace(/[^0-9\.]/g, ''); 
     } else if ($(this).val() > 500) { 
      $(this).val('500'); 
     } else if ($(this).val() < 0) { 
      $(this).val('0'); 
     } 
    }); 

    $('#minDistance').blur(function() { 
     if ($(this).val() > $('#maxDistance').val()) { 
      $(this).val('0'); 
     } 
    }); 

    function sendForm(e) { 
     e.preventDefault(); 
     var formData = new FormData(); 

     formData.append('percentageOfMessages', $('#percentageOfMessages').val()); 

     if ($('RemoveDeletedAccounts').prop('checked')) { 
      formData.append('RemoveDeletedAccounts', "1"); 
     } else { 
      formData.append('RemoveDeletedAccounts', "0"); 
     } 

     if ($('RemoveNoReply').prop('checked')) { 
      formData.append('RemoveNoReply', "1"); 
     } else { 
      formData.append('RemoveNoReply', "0"); 
     } 

     if ($('RemoveNoResponse').prop('checked')) { 
      formData.append('RemoveNoResponse', "1"); 
     } else { 
      formData.append('RemoveNoResponse', "0"); 
     } 

     formData.append('minMatchPercent', $('#minMatchPercent').val()); 
     //OTHER STUFFFFFFFFF 
$.ajax({ 
      type: 'POST', 

      xhr: function() { // Custom XMLHttpRequest 
       var myXhr = $.ajaxSettings.xhr(); 
       if (myXhr.upload) { // Check if upload property exists 
        //myXhr.upload.addEventListener('progress',progressHandlingFunction, false); // For handling the progress of the upload 
       } 
       return myXhr; 
      }, 
      cache: false, 
      processData: false, 
      contentType: false, 
      data: formData, 
      url: 'addAccounts.php', 
      success: function(data) { 
       console.log(data); 
      }, 
      error: function(xhr, err) { 
       console.log("readyState: " + xhr.readyState + "\nstatus: " + xhr.status); 
       console.log("responseText: " + xhr.responseText); 
      } 
     }); 

    } 

這裏是HTML

<div class="row uniform"> 
    <div class="6u 12u$(xsmall)"> 
     <input type="text" name="minDistance" id="minDistance" value="0" /> 
    </div> 
    <div class="6u 12u$(xsmall)"> 
     <input type="text" name="maxDistance" id="maxDistance" value="500" /> 

    </div> 
</div> 

Answer 1

返回FALSE如果VAR存在並具有非空的非零值。 否則返回TRUE。
下面的事情被認爲是空的：

• "" (an empty string)
• 0 (0 as an integer)
• 0.0 (0 as a float)
• "0" (0 as a string)
• NULL
• FALSE
• array() (an empty array)
• $var; (a variable declared, but without a value)

代碼示例：

// Evaluates to true because $var is empty 
if (empty($var)) { 
    echo '$var is either 0, empty, or not set at all'; 
} 
// Evaluates as true because $var is set 
if (isset($var)) { 
    echo '$var is set even though it is empty'; 
} 

根據manual0或"0"將被認爲是空的，你可以使用isset()代替。