位和位掩码是我一直在努力理解的东西，但是我想学习如何在PHP中使用它们进行设置和类似操作。

我终于找到了一个声称完全可以做到这一点的类，而且据我所知，它似乎可以工作，但是我不确定这是否是实现此目的的最佳方法。我将使用下面的示例代码发布类文件，以按工作顺序显示它。

如果您有经验，请告诉我是否可以改进，性能或其他方面。我真的很想学习这一点，而且我一直在阅读它，但是到目前为止，这对我来说很难理解。

班级…

<?php
    class bitmask
    {
        /**
         * This array is used to represent the users permission in usable format.
         *
         * You can change remove or add valuesto suit your needs.
         * Just ensure that each element defaults to false. Once you have started storing
         * users permsisions a change to the order of this array will cause the
         * permissions to be incorectly interpreted.
         *
         * @type Associtive array
         */
        public $permissions = array(
                                    "read" => false,
                                    "write" => false,
                                    "delete" => false,
                                    "change_permissions" => false,
                                    "admin" => false
                                    );

        /**
         * This function will use an integer bitmask (as created by toBitmask())
         * to populate the class vaiable
         * $this->permissions with the users permissions as boolean values.
         * @param int $bitmask an integer representation of the users permisions.
         * This integer is created by toBitmask();
         *
         * @return an associatve array with the users permissions.
         */
        public function getPermissions($bitMask = 0)
        {
            $i = 0;
            foreach ($this->permissions as $key => $value)
            {
                $this->permissions[$key] = (($bitMask & pow(2, $i)) != 0) ? true : false;

                // Uncomment the next line if you would like to see what is happening.
                //echo $key . " i= ".strval($i)." power=" . strval(pow(2,$i)). "bitwise & = " . strval($bitMask & pow(2,$i))."<br>";
                $i++;
            }
            return $this->permissions;
        }

        /**
         * This function will create and return and integer bitmask based on the permission values set in
         * the class variable $permissions. To use you would want to set the fields in $permissions to true for the permissions you want to grant.
         * Then call toBitmask() and store the integer value.  Later you can pass that integer into getPermissions() to convert it back to an assoicative
         * array.
         *
         * @return int an integer bitmask represeting the users permission set.
         */
        function toBitmask()
        {
            $bitmask = 0;
            $i = 0;
            foreach ($this->permissions as $key => $value)
            {

                if ($value)
                {
                    $bitmask += pow(2, $i);
                }
                $i++;
            }
            return $bitmask;
        }
    }
?>

如何将权限设置/保存为位掩码值？

<?php
    /**
     * Example usage
     * initiate new bitmask object
     */
    $perms = new bitmask();

    /**
     * How to set permissions for a user
     */
    $perms->permissions["read"] = true;
    $perms->permissions["write"] = true;
    $perms->permissions["delete"] = true;
    $perms->permissions["change_permissions"] = true;
    $perms->permissions["admin"] = false;

    // Converts to bitmask value to store in database or wherever
    $bitmask = $perms->toBitmask();  //in this example it is 15
    $sql = "insert into user_permissions (userid,permission) values(1,$bitmask)";
    echo $sql; //you would then execute code to insert your sql.
?>

取得位掩码值并基于位值为每个数组项返回true / false的示例。

<?php
    /**
     * Example usage to get the bitmask value from database or session/cache.... then put it to use.
     * $permarr returns an array with true/false for each array value based on the bit value
     */
    $permarr = $perms->getPermissions($bitmask);

    if ($permarr["read"])
    {
        echo 'user can read: <font color="green">TRUE</font>';
    }
    else {
        echo 'user can read: <font color="red">FALSE</font>';
    }

    //user can WRITE permission
    if ($permarr["write"])
    {
        echo '<br>user can write: <font color="green">TRUE</font>';
    }
    else {
        echo '<br>user can write: <font color="red">FALSE</font>';
    }
?>