PHP判断数组（多维数组）值是否为空

//array_filter() 将删除 $res 中所有等值为 FALSE 的条目
$filter_res = array_filter($res);

if(!empty($filter_res))
{
     //数组不为空的操作
}
else
{
    //数组为空的操作
}

<?php
//上面把你要判断的数组放在这，名字是$shuzu
foreach ($shuzu as $v1)  
{ 
foreach ($v1 as $v2)  
{ 
//print "$v2";
$shunzi =$shunzi.$v2;
}
if($shunzi=="")
{
echo "数组是空的";
}
else
{
echo "数组有元素";
}
?>

count($arr),size($arr);

$arr= array("");
echo count($arr);
echo size($arr);
//输出1

class Test{
public static function array_is_null($arr = null){
if(is_array($arr)){
foreach($arr as $k=>$v){
if($v&&!is_array($v)){
return false;
}
$t = self::array_is_null($v);
if(!$t){
return false;
}
}
return true;
}elseif(!$arr){
return true;
}else{
return false;
}
}
}

<?php
      
        //判断临时文件存放路径是否包含用户上传的文件
        if(is_uploaded_file($_FILES["uploadfile"]["tmp_name"])){
        //为了更高效，将信息存放在变量中
        $upfile=$_FILES["uploadfile"];//用一个数组类型的字符串存放上传文件的信息
        //print_r($upfile);//如果打印则输出类似这样的信息Array ( [name] => m.jpg [type] => image/jpeg [tmp_name] => C:WINDOWSTempphp1A.tmp [error] => 0 [size] => 44905 )
        $name=$upfile["name"];//便于以后转移文件时命名
        $type=$upfile["type"];//上传文件的类型
        $size=$upfile["size"];//上传文件的大小
        $tmp_name=$upfile["tmp_name"];//用户上传文件的临时名称
        $error=$upfile["error"];//上传过程中的错误信息
        //echo $name;
        //对文件类型进行判断，判断是否要转移文件,如果符合要求则设置$ok=1即可以转移
        switch($type){
            case "image/jpg": $ok=1;
            break;
            case "image/jpeg": $ok=1;
            break;
            case "image/gif" : $ok=1;
            break;
            default:$ok=0;
            break;
        }
        //如果文件符合要求并且上传过程中没有错误
        if($ok&&$error=='0'){
            //调用move_uploaded_file（）函数，进行文件转移
            move_uploaded_file($tmp_name,'up/'.$name);
            //操作成功后，提示成功
            echo "<script language="javascript">alert('succeed')</script>";
        }else{
            //如果文件不符合类型或者上传过程中有错误，提示失败
            echo "<script language="javascript">alert('failed')</script>";
        }
    }
?>
<!--设置提交文件的表单-->
<form enctype="multipart/form-data" method="post" name="uploadform">
<input type="file" name="uploadfile" value="Upload File">
<input type="submit" name="submit" value="Upload">
</form>

function FileUpload( $resourceType, $currentFolder, $sCommand )
{
 if (!isset($_FILES)) {
  global $_FILES;
 }
 $sErrorNumber = '0' ;
 $sFileName = '' ;

 if ( isset( $_FILES['NewFile'] ) && !is_null( $_FILES['NewFile']['tmp_name'] ) )
 {
  global $Config ;

  $oFile = $_FILES['NewFile'] ;

  // Map the virtual path to the local server path.
  $sServerDir = ServerMapFolder( $resourceType, $currentFolder, $sCommand ) ;

  // Get the uploaded file name.
  $sFileName = $oFile['name'] ;
  $sFileName = SanitizeFileName( $sFileName ) ;

  $sOriginalFileName = $sFileName ;

  // Get the extension.
  $sExtension = substr( $sFileName, ( strrpos($sFileName, '.') + 1 ) ) ;
  $sExtension = strtolower( $sExtension ) ;

  if ( isset( $Config['SecureImageUploads'] ) )
  {
   if ( ( $isImageValid = IsImageValid( $oFile['tmp_name'], $sExtension ) ) === false )
   {
    $sErrorNumber = '202' ;
   }
  }

  if ( isset( $Config['HtmlExtensions'] ) )
  {
   if ( !IsHtmlExtension( $sExtension, $Config['HtmlExtensions'] ) &&
    ( $detectHtml = DetectHtml( $oFile['tmp_name'] ) ) === true )
   {
    $sErrorNumber = '202' ;
   }
  }

  // Check if it is an allowed extension.
  if ( !$sErrorNumber && IsAllowedExt( $sExtension, $resourceType ) )
  {
   $iCounter = 0 ;

   while ( true )
   {
    $sFilePath = $sServerDir . $sFileName ;

    if ( is_file( $sFilePath ) )
    {
     $iCounter++ ;
     $sFileName = RemoveExtension( $sOriginalFileName ) . '(' . $iCounter . ').' . $sExtension ;
     $sErrorNumber = '201' ;
    }
    else
    {
     move_uploaded_file( $oFile['tmp_name'], $sFilePath ) ;

     if ( is_file( $sFilePath ) )
     {
      if ( isset( $Config['ChmodOnUpload'] ) && !$Config['ChmodOnUpload'] )
      {
       break ;
      }

      $permissions = 0777;

      if ( isset( $Config['ChmodOnUpload'] ) && $Config['ChmodOnUpload'] )
      {
       $permissions = $Config['ChmodOnUpload'] ;
      }

      $oldumask = umask(0) ;
      chmod( $sFilePath, $permissions ) ;
      umask( $oldumask ) ;
     }

     break ;
    }
   }

   if ( file_exists( $sFilePath ) )
   {
    //previous checks failed, try once again
    if ( isset( $isImageValid ) && $isImageValid === -1 && IsImageValid( $sFilePath, $sExtension ) === false )
    {
     @unlink( $sFilePath ) ;
     $sErrorNumber = '202' ;
    }
    else if ( isset( $detectHtml ) && $detectHtml === -1 && DetectHtml( $sFilePath ) === true )
    {
     @unlink( $sFilePath ) ;
     $sErrorNumber = '202' ;
    }
   }
  }
  else
   $sErrorNumber = '202' ;
 }
 else
  $sErrorNumber = '202' ;

 $sFileUrl = CombinePaths( GetResourceTypePath( $resourceType, $sCommand ) , $currentFolder ) ;
 $sFileUrl = CombinePaths( $sFileUrl, $sFileName ) ;

 SendUploadResults( $sErrorNumber, $sFileUrl, $sFileName ) ;

 exit ;

if( isset($_GET[’name’]) )//判断传来的值是否为空。 
{ 
       echo "值为空"; 
} 

$sql = "select * form abc"
$result = mysql_query($sql);
$row = mysql_fetch_array($result);
if(!$row)//开始判断是够为空
{
echo "null";
}
else
{
echo "not null";
}

$a = null;
$b = false;
if (is_null($a)) echo '$a 为NULL' . "";
if (is_null($b)) echo '$b 为NULL' . "";
if (is_null($c)) echo '$c 为NULL' . "";
// 显示结果为
// $a 为NULL
// Undefined variable: c

function get_keywords($html)
{
$html=strtolower($html);
preg_match("@<head[^>]*>(.*?)</head>@si",$html, $regs); 
$headdata = $regs[1];
preg_match("/<meta +name *=["']?keywords["']? *content=["']?([^<>"]+)["']?/i", $headdata, $res);
if (isset ($res)) {
$keywords = $res[1];
}
if ($keywords == "") $keywords = "无";
$keywords=replace_word(textcut($keywords,250));
$keywords=str_replace("-",",",$keywords);
$keywords=str_replace("，",",",$keywords);
$keywords=str_replace(" ",",",$keywords);
$keywords=str_replace("|",",",$keywords);
$keywords=str_replace("、",",",$keywords);
$keywords=str_replace(",,",",",$keywords);
$keywords=str_replace("<","",$keywords);
$keywords=str_replace(">","",$keywords);
return addslashes(trim($keywords));
}

function get_title($html)
{
  $html=strtolower($html);
 $title = str_replace(" - ",",",cut($html,"<title>", "</title>" ));
//if ($title == "") $title = "无标题";
if ($title) $title=replace_word(textcut($title,80));
if ($title) $title=preg_replace("/<(.*?)>/","",$title);
return addslashes(trim($title));
}

function get_description($html)
{
$html=strtolower($html);
preg_match("@<head[^>]*>(.*?)</head>@si",$html, $regs); 
$headdata = $regs[1];
preg_match("/<meta +name *=["']?description["']? *content=["']?([^<>"]+)["']?/i", $headdata, $res);
      if (isset ($res)) {
       $description = $res[1];
      }
if ($description == "") $description = "无";
$description=replace_word(textcut($description,250));
$description=str_replace("-",",",$description);
$description=str_replace("，",",",$description);
$description=str_replace(" ",",",$description);
$description=str_replace("|",",",$description);
$description=str_replace("、",",",$description);
$description=str_replace(",,",",",$description);
$description=str_replace("<","",$description);
$description=str_replace(">","",$description);
return addslashes(trim($description));
}

file_delete = "home/meeta/my.php";

if (unlink($file_delete)) {
echo "The file was deleted successfully.", "n";
} else {
echo "The specified file could not be deleted. Please try again.", "n";
}
?>

$myfile = "./test1.txt";
if (file_exists($myfile)) {
$result=unlink ($myfile);
echo $result;
}
?>

<?php
function del_dir($dir){    //删除目录
    if(!($mydir=@dir($dir))){
        return;
    }
    while($file=$mydir->read()){
        if(is_dir("$dir$file") && $file!='.' && $file!='..'){
            @chmod("$dir$file", 0777);
            del_dir("$dir$file");
        }elseif(is_file("$dir/$file")){
            $file_time=@stat($file);    //读取文件的最后更新时间
            if(time()-$file_time>3600*24*14){
                @chmod("$dir/$file", 0777);
                @unlink("$dir/$file");
            }
        }
    }
    $mydir->close();
    @chmod($dir, 0777);
    @rmdir($dir);
}
?>