小编use*_*857的帖子

我有一个类似于此的单例类

public class Singleton
{
    private static Singleton m_instance;
    private Timer m_timer;
    private static List<CustomObject> m_cacheObjects;

    private Singleton()
    {    
        m_cacheObjects = new List<CustomObject>();
        m_timer= new Timer(MyTimerCallBack, 
                           null, 
                           TimeSpan.FromSeconds(60), 
                           TimeSpan.FromSeconds(60));           
    }

    public static Singleton Instance
    {
        get
        {
            if (m_instance == null)
            {
                m_instance = new Singleton();
            }
            return m_instance;
        }
    }

    private void MyTimerCallBack(object state)
    {
        //******** Update the list by interval here ******************

        m_cacheObjects = UpdateTheList();
    }

    public void CallMe()
    {
        foreach (CustomObject obj in m_cacheObjects)
        {
            // do …

我有一个if if语句,它永远不会返回True.怎么了？

我是php和regex的新手.

$String = '123456'; 
$Pattern = "/\d{2}$/"; 

//i intend to match '56', which is the last two digit of the string.

if(preg_match($Pattern $String ,$matches))
{
 echo 'Matched';
}

如果$Pattern是"/^\d{2}/",则返回true并匹配数字'12';

编辑:我的错误.上面的代码运行良好.在实际的代码中,$ String是从变量中分配的,而alwasys最终得到了一个我不知道的点.匹配上面最后两位数的要求仅用于问题解释.在实际代码中需要正则表达式.