雅虎公司C#笔试题(2) - 面试

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

雅虎公司C#笔试题(2)(二)