Question

我制作了这种点数系统，用户可以花点积分。用户点数会被扣除。我没有包含很多变量，但它们都没问题。问题出现在return($success)和return($error_message)。

以下是代码：

function died($error) {
    header("Location: error_points_on.php?error=" . $error);
    die();
}

function success($success) {
    header("Location: success_points_on.php?success=" . $success);
    die();
}
function quote_smart($value, $handle) {

if (get_magic_quotes_gpc()) {
$value = stripslashes($value);
}

if (!is_numeric($value)) {
$value = "'" . mysql_real_escape_string($value, $handle) . "'";
}
return $value;
}

function product($price,$points, $name, $uname, $error_message, $success_message) {


    $user_name = "cencord";
    $pass_word = "cencord";
    $database = "cencord";
    $server = "cencord";

    $db_handle = mysql_connect($server, $user_name, $pass_word);
    $db_found = mysql_select_db($database, $db_handle);

 if ($db_found) { // connect to DB

            $uname = quote_smart($uname, $db_handle);
            $SQL = mysql_query("SELECT points FROM members WHERE username=$uname");
            $points = mysql_fetch_row($SQL);

            $points = $points[0]; // make it a variable rather then an array


    if ($points >= $price) {

         $points = $points-$price; // fjern points

         $points = quote_smart($points, $db_handle);

         mysql_query("UPDATE members SET points=$points WHERE username = $uname");

         $success_message .= "The " . $name . " has been mailed to your E-mail, please allow 5 minutes for it to arrive.<br />";
         return($success_message);
    }


        else if ($points < $price) {

        $error_message .= "You have " . $points . " you need " . $price . " points to purchase a " . $name;
        return($error_message);
        }

else if (!$db_found) {
$error_message .= "Could not connect to the database, please contact support";
return($error_message);
    }
}
}



  if($Checked1 == true) {
      product(400, $points, "Some string", $uname,     $error_message, $success_message); //price and name
}
  if($Checked2 == true) {

      product(400, $points, "Some string", $uname,     $error_message, $success_message);
}



 if(strlen($error_message) > 0) {
    died($error_message);
  }
 if(strlen($success_message) > 0) {
    success($success_message);
  }

echo "error didnt pass at all";

我可以添加

header("Location: success_points_on.php?success=" . $success);

而不是返回，但我希望用户能够购买多个项目（添加它而不是返回确实有效）。

Answer 1

您的逻辑嵌套错误。剥离内容并只留下if语句，你有product()函数：

function product($price,$points, $name, $uname, $error_message, $success_message) {
    if ($db_found) { // connect to DB
        if ($points >= $price) {
            $success_message = "blah";
            return($success_message);
        } 
        else if ($points < $price) {  // This if () part is redundant, btw
            $error_message = "blah";
            return($error_message);
        }
        else if (!$db_found) {
            $error_message .= "blah"; // This should be = instead of .=
            return($error_message);
        }
    }
}

你想要的是：

function product($price,$points, $name, $uname, &$error_message, &$success_message) {
    if ($db_found) { 
        if ($points >= $price) {
            $success_message = "blah";
            return($success_message); // this is redundant actually
        } else {
            $error_message = "blah";
            return($error_message);  // this is redundant actually
        }
    } else {
        $error_message = "blah";
        return($error_message);  // this is redundant actually
    }
}

我强烈建议使用某些工具，例如IDE，它可以使您的代码格式正确，这样可以更容易地看到这些类型的问题。

修改

我还注意到你没有通过引用传递$ error_message和$ success_message，这将导致更多问题。上面做出的更改（在第二个示例中），但此代码仍然不是我称之为最佳实践。

Answer 2

我同意@leftclickben上面所说的一切，但是想再添加一个观察。我似乎在您致电$error_message之后的代码中使用$success_message和product()的值，但为了让功能更改它们的价值，您必须通过参考，使用&符号。

将您的函数原型更改为

function product($price,$points, $name, $uname, &$error_message, &$success_message) {

，函数返回后，值的变化将可用。

函数及其返回值的问题

2 个答案: