php演算法看不懂，請高手逐句給解釋下吧！該怎麼處理

php演算法看不懂，請高手逐句給解釋下吧！急急
$MM_paramName = "";?

// *** Go To Record and Move To Record: create strings for maintaining URL and Form parameters
// create the list of parameters which should not be maintained
$MM_removeList = "&index=";
if ($MM_paramName != "") $MM_removeList .= "&".strtolower($MM_paramName)."=";
$MM_keepURL="";
$MM_keepForm="";
$MM_keepBoth="";
$MM_keepNone="";
// add the URL parameters to the MM_keepURL string
reset ($HTTP_GET_VARS);
while (list ($key, $val) = each ($HTTP_GET_VARS)) {
$nextItem = "&".strtolower($key)."=";
if (!stristr($MM_removeList, $nextItem)) {
$MM_keepURL .= "&".$key."=".urlencode($val);
}
}
// add the URL parameters to the MM_keepURL string
if(isset($HTTP_POST_VARS)){
reset ($HTTP_POST_VARS);
while (list ($key, $val) = each ($HTTP_POST_VARS)) {
$nextItem = "&".strtolower($key)."=";
if (!stristr($MM_removeList, $nextItem)) {
$MM_keepForm .= "&".$key."=".urlencode($val);
}
}
}
// create the Form + URL string and remove the intial '&' from each of the strings
$MM_keepBoth = $MM_keepURL."&".$MM_keepForm;
if (strlen($MM_keepBoth) > 0) $MM_keepBoth = substr($MM_keepBoth, 1);
if (strlen($MM_keepURL) > 0) $MM_keepURL = substr($MM_keepURL, 1);
if (strlen($MM_keepForm) > 0) $MM_keepForm = substr($MM_keepForm, 1);

------解決方案--------------------
把GET參數和POST參數重新全部拼接到GET參數裡，形成一個URL叫做MM_keepBoth，由於拼接時採取了. &key=val，所以字串開始多了一個&, 需要substr刪掉。

------解決方案--------------------
來試試看。

PHP code

 $MM_paramName = ""; // *** Go To Record and Move To Record: create strings for maintaining URL and Form parameters// create the list of parameters which should not be maintained$MM_removeList = "&index=";if ($MM_paramName != "") $MM_removeList .= "&".strtolower($MM_paramName)."=";  $MM_keepURL="";$MM_keepForm="";$MM_keepBoth="";$MM_keepNone="";// add the URL parameters to the MM_keepURL stringreset ($HTTP_GET_VARS);   //$HTTP_GET_VARS等價於$_GET。早起的php3/4版本都是用$HTTP_GET_VARS，不過到了後來版本$HTTP_GET_VARS被棄用了。改用$_GET 了。while (list ($key, $val) = each ($HTTP_GET_VARS)) {   //遍曆數組每項，鍵=$key,值=$val$nextItem = "&".strtolower($key)."=";if (!stristr($MM_removeList, $nextItem)) {   //如果MM_removeList中不存在$nextItem$MM_keepURL .= "&".$key."=".urlencode($val);  //連接字串}}// add the URL parameters to the MM_keepURL stringif(isset($HTTP_POST_VARS)){  //$HTTP_POST_VARS同$HTTP_GET_VARSreset ($HTTP_POST_VARS);  //重設$HTTP_POST_VARS,使其指標回到0while (list ($key, $val) = each ($HTTP_POST_VARS)) {  //遍曆，同上$nextItem = "&".strtolower($key)."=";    //連接字串if (!stristr($MM_removeList, $nextItem)) {   //同上$MM_keepForm .= "&".$key."=".urlencode($val);  //同上}}}// create the Form + URL string and remove the intial '&' from each of the strings$MM_keepBoth = $MM_keepURL."&".$MM_keepForm;if (strlen($MM_keepBoth) > 0) $MM_keepBoth = substr($MM_keepBoth, 1);   //如果$MM_keepBoth位元組長度大於0，則從1位元組位置截取到末尾if (strlen($MM_keepURL) > 0) $MM_keepURL = substr($MM_keepURL, 1);    //類似上面if (strlen($MM_keepForm) > 0) $MM_keepForm = substr($MM_keepForm, 1);   //類似上面
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