静态导入

// 静态的using声明允许调用静态方法时不使用类名
// C# 5
using System;
​
Console.WriteLine("C# 5");
​
// C# 6
using static System.Console;
​
WriteLine("C# 6");

表达式体方法

// C# 5
public bool IsSquare(Rectangle rect)
{
     return rect.Width == rect.Height;
}
​
// C# 6
public bool IsSquare(Rectangle rect) => rect.Width == rect.Height;

表达式体属性

// C# 5
public string FullName
{
    get
    {
        return FirstName + " " + LastName;
    }
}
​
// C# 6
public string FullName => FirstName + " " + LastName;

自动实现的属性初始化器

// C# 5
public class Person
{
    public Person()
    {
        Age = 24;
    }
    public int Age { get; set; }
}
​
// C# 6
public class Person
{
    public int Age { get; set; } = 24;
}

自动属性-只读

// C# 5
private readonly int _bookId;
public BookId
{
    get
    {
        return _bookId;
    }
}
​
// C# 6
private readonly int _bookId;
public BookId { get; }

nameof运算符

// nameof表达式在编译时进行求值，在运行时无效
​
// C# 5
public void Method(object o)
{
    if(o == null)
    {
        throw new ArgumentNullException("o");
    }
}
​
// C# 6
public void Method(object o)
{
    if(o == null)
     {
        throw new ArgumentNullException(nameof(o));
    }
}

空值传播运算符

// C# 5
int? age = p == null ? null : p.Age;
​
// C# 6
int? age = p?.Age;

字符串内插

// C# 5
public override string ToString()
{
    return string.Format("{0},{1}", Title, Publisher);
}
​
// C# 6
public override string ToString() => $"{Title}{Publisher}";

字典初始化

// C# 5
var dic = new Dictionary<int, string>();
dic.Add(3, "three");
dic.Add(7, "seven");
​
// C# 6
var dic = new Dictionary<int, string>()
{
    [3] = "three",
    [7] = "seven"
};

异常过滤器

// C# 5
try
{
      //
}
catch (MyException ex)
{
    if (ex.ErrorCode != 405) throw;
}
​
// C# 6
try
{
      //
}
catch (MyException ex) when (ex.ErrorCode == 405)
{
    //
}

catch中的await

// C# 5
bool hasError = false;
string errorMsg = null;
try
{
    //
}
catch (MyException ex)
{
    hasError = true;
    errorMsg = ex.Message;
}
if (hasError)
{
    await new MessageDialog().ShowAsync(errorMsg);
}
​
// C# 6
try
{
    //
}
catch (MyException ex)
{
    await new MessageDialog().ShowAsync(ex.Message);
}