崔景宇 => 第一周作业

//第二题
$img = <<<IMG
asdjlasjdklasjdlkasjdlkjaslkdjasdassdasdasd <img src="http://www.baidu.com/img/bd1.gif" onclick="demo()" width="278" height="127" /> asdasdasdasdqweioqwueiasjkhdjkacj
<img src="http://www.baidu.com/img/logo2.jpeg" WIDTH = " 275px " height="179px" > <a>asdasdasdasdasdasdasd>
<img src="http://www.baidu.com/img/logo2.jpg" width=" 123123 " height="adasdasd" >
qweqweqweqweqwewqe<>
IMG;
    
$pattern = "#\<img.*src\=\".+\.(gif|jpg|jpeg)\".+(width\s*\=\s*\")(.+\").+(heights*\=\s*\")(.+\").*\>#iUs";
    
$callBack = function ( $result ) {
    
        $findArr = array(
                        0 => $result[2].$result[3],
                        1 => $result[4].$result[5],
                        2 => $result[1]
                );
            
        $replaceArr = array(
                        0 => $result[4].$result[3],
                        1 => $result[2].$result[5],
                        2 => 'png'
                );
            
        foreach ($findArr as $key => $find ) {
                $result[0] = str_replace( $find, $replaceArr[$key], $result[0] );
        }
    
        return $result[0];
    
};
    
    
$img = preg_replace_callback( $pattern, $callBack, $img );
 
//第三题
$str = 'qweqweqwe';
$key = 'woshikey';
    
$str = encryption( $str, $key );
var_dump( $str );
    
$str = encryption( $str, $key, 'DECODE' );
var_dump( $str );
    
function encryption( $str, $key, $do = 'ENDCODE' ) {
    
        $do == 'DECODE' && $str = base64_decode( $str );
            
        $strLen = strlen( $str );
        $key = md5( $key );
        $keyLen = strLen( $key );
            
        for( $i = 0; $i < strlen( $str ); $i++ ) {
                $index = $i % $keyLen;
                $do == 'DECODE' && $str[$i] = chr( ord( $str[$i] ) - $i );
                $str[$i] = $str[$i] ^ $key[ $index ];
                $do == 'ENDCODE' && $str[$i] = chr( ord( $str[$i] ) + $i );
        }
            
        $do == 'ENDCODE' && $str = base64_encode( $str );
            
        return $str;
}