is_array -- 检测变量是否是数组

is_array -- 检测变量是否是数组
 描述
 bool is_array ( mixed var)
 
 
 如果 var 是 array，则返回 TRUE，否则返回 FALSE。

 is_array($array)
 判断一个值是否为数组
 */
 $array = array('','');
 if( is_array( $array ) )
 {
  echo 'is array';
 }
 
 // 输出结果 is array
 
 $str ='';
 if( is_array( $str ) )
 {
  echo 'is array';
 }
 else
 {
  echo 'is string';
 }
 
 //输出结果为is string

php 删除cookie有效方法
关于删除cookie的说明开始-----

bool setcookie ( string name [, string value [, int expire [, string path [, string domain [, bool secure]]]]] )

要删除cookie需要确保它的失效期是在过去，才能触发浏览器的删除机制。

下面的例子说明了如何删除刚才设置的cookie：
<?php
//将过期时间设为一小时前
setcookie("TestCookie", "", time() - 3600);
setcookie("TestCookie", "", time() - 3600, "/~rasmus/", ".utoronto.ca", 1);
?>

-----关于删除cookie的说明结束-----

删除一个cookie的方法就是把这个cookie的有效期设置为当前时间以前，这也是几乎所有php程序员都会这么做。

后来一个初接触php的朋友告诉我，他在程序中本想把一个cookie的值设置为空，结果导致这个cookie直接被删除。我当时的第一反应是不相信，于是测试
了一下：
setcookie("testcookie", '');
print_r($_COOKIE);

结果果然是整个$_COOKIE数组都是空的，而非仅仅$_COOKIE['testcookie']为空。于是用winsock抓包，观察返回的http头，发现http头竟然是“Set-Cookie: testcookie=deleted; expires=Mon, 18-Jun-2007 02:42:33 GMT”，这说明“setcookie("testcookie", '');”的的确确是将testcookie这个cookie直接删除，而关于这种情况在php手册中完全没有说明。

最后阅读php源码，终于发现真相（这就是开源的好处了，有什么不清楚的内幕，直接查源码）。

以下代码可以在php5.20的linux源码包中ext/standard/head.c第99行附近找到：
if (value && value_len == 0) {
    /*
     * MSIE doesn't delete a cookie when you set it to a null value
     * so in order to force cookies to be deleted, even on MSIE, we
     * pick an expiry date 1 year and 1 second in the past
     */
    time_t t = time(NULL) - 31536001;
    dt = php_format_date("D, d-M-Y H:i:s T", sizeof("D, d-M-Y H:i:s T")-1, t, 0 TSRMLS_CC);
    sprintf(cookie, "Set-Cookie: %s=deleted; expires=%s", name, dt);
    efree(dt);
} else {
    sprintf(cookie, "Set-Cookie: %s=%s", name, value ? encoded_value : "");
    if (expires > 0) {
        strcat(cookie, "; expires=");
        dt = php_format_date("D, d-M-Y H:i:s T", sizeof("D, d-M-Y H:i:s T")-1, expires, 0 TSRMLS_CC);
        strcat(cookie, dt);
        efree(dt);
    }
}

源码中清清楚楚的显示“if (value && value_len == 0)”，当“value_len”为0时，“sprintf(cookie, "Set-Cookie: %s=deleted; expires=%s", name, dt);”会发送删除cookie的http头给浏览器。

最后我们可以得出结论：在php中使用“setcookie($cookiename, '');”或者“setcookie($cookiename, NULL);”都会删除cookie，当然这些手册中并没有。

php文件上传经典代码

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 ;

php创建文件夹函数

function CreateFolder( $resourceType, $currentFolder )
{
 if (!isset($_GET)) {
  global $_GET;
 }
 $sErrorNumber = '0' ;
 $sErrorMsg  = '' ;

 if ( isset( $_GET['NewFolderName'] ) )
 {
  $sNewFolderName = $_GET['NewFolderName'] ;
  $sNewFolderName = SanitizeFolderName( $sNewFolderName ) ;

  if ( strpos( $sNewFolderName, '..' ) !== FALSE )
   $sErrorNumber = '102' ;  // Invalid folder name.
  else
  {
   // Map the virtual path to the local server path of the current folder.
   $sServerDir = ServerMapFolder( $resourceType, $currentFolder, 'CreateFolder' ) ;

   if ( is_writable( $sServerDir ) )
   {
    $sServerDir .= $sNewFolderName ;

    $sErrorMsg = CreateServerFolder( $sServerDir ) ;

    switch ( $sErrorMsg )
    {
     case '' :
      $sErrorNumber = '0' ;
      break ;
     case 'Invalid argument' :
     case 'No such file or directory' :
      $sErrorNumber = '102' ;  // Path too long.
      break ;
     default :
      $sErrorNumber = '110' ;
      break ;
    }
   }
   else
    $sErrorNumber = '103' ;
  }
 }
 else
  $sErrorNumber = '102' ;

 // Create the "Error" node.
 echo '<Error number="' . $sErrorNumber . '" originalDescription="' . ConvertToXmlAttribute( $sErrorMsg ) . '" />' ;
}

php 读取文件夹文件函数

function GetFoldersAndFiles( $resourceType, $currentFolder )
{
 // Map the virtual path to the local server path.
 $sServerDir = ServerMapFolder( $resourceType, $currentFolder, 'GetFoldersAndFiles' ) ;

 // Arrays that will hold the folders and files names.
 $aFolders = array() ;
 $aFiles  = array() ;

 $oCurrentFolder = opendir( $sServerDir ) ;

 while ( $sFile = readdir( $oCurrentFolder ) )
 {
  if ( $sFile != '.' && $sFile != '..' )
  {
   if ( is_dir( $sServerDir . $sFile ) )
    $aFolders[] = '<Folder name="' . ConvertToXmlAttribute( $sFile ) . '" />' ;
   else
   {
    $iFileSize = @filesize( $sServerDir . $sFile ) ;
    if ( !$iFileSize ) {
     $iFileSize = 0 ;
    }
    if ( $iFileSize > 0 )
    {
     $iFileSize = round( $iFileSize / 1024 ) ;
     if ( $iFileSize < 1 ) $iFileSize = 1 ;
    }

    $aFiles[] = '<File name="' . ConvertToXmlAttribute( $sFile ) . '" size="' . $iFileSize . '" />' ;
   }
  }
 }

 // Send the folders
 natcasesort( $aFolders ) ;
 echo '<Folders>' ;

 foreach ( $aFolders as $sFolder )
  echo $sFolder ;

 echo '</Folders>' ;

 // Send the files
 natcasesort( $aFiles ) ;
 echo '<Files>' ;

 foreach ( $aFiles as $sFiles )
  echo $sFiles ;

 echo '</Files>' ;
}