ompiler offers compile time checking for backward compatibility.
4. It doesn’t.
Question 49. (单选)
三种常用的字符串判空串方法：
1: bool isEmpty = (str.Length == 0);
2: bool isEmpty = (str == String.Empty);
3: bool isEmpty = (str == “”);
哪种方法最快？
1. 1
2. 2
3. 3
Question 50. (单选)
public sealed class SampleSingleton1
{
private int m_Counter = 0;
private SampleSingleton1()
{
Console.WriteLine(“”初始化SampleSingleton1。”");
}
public static readonly SampleSingleton1 Singleton = new SampleSingleton1();
public void Counter()
{
m_Counter ++;
}
}
以上代码实现了设计模式中的哪种模式？
1. 原型
2. 抽象工厂
3. 单键
4. 生成器