php的功能(11)

    *@tmpname - temporary path to thumbnail 
    *@xmax - max width 
    *@ymax - max height 
    */  
    function resize_image($filename, $tmpname, $xmax, $ymax)  
    {  
        $ext = explode(".", $filename);  
        $ext = $ext[count($ext)-1];    
      
        if($ext == "jpg" || $ext == "jpeg")  
            $im = imagecreatefromjpeg($tmpname);  
        elseif($ext == "png")  
            $im = imagecreatefrompng($tmpname);  
        elseif($ext == "gif")  
            $im = imagecreatefromgif($tmpname);    
      
        $x = imagesx($im);  
        $y = imagesy($im);    
      
        if($x <= $xmax && $y <= $ymax)  
            return $im;    
      
        if($x >= $y) {  
            $newx = $xmax;  
            $newy = $newx * $y / $x;  
        }  
        else {  
            $newy = $ymax;  
            $newx = $x / $y * $newy;  
        }    
      
        $im2 = imagecreatetruecolor($newx, $newy);  
        imagecopyresized($im2, $im, 0, 0, 0, 0, floor($newx), floor($newy), $x, $y);  
        return $im2;  
    }  
1. PHP可阅读随机字符串

　　此代码将创建一个可阅读的字符串，使其更接近词典中的单词，实用且具有密码验证功能。

    /**************
    *@length - length of random string (must be a multiple of 2)