$ 和 @ 的用法 - 爱码网

$ - 字符串内插

从 C# 6 开始可以使用此功能。

之间不能有任何空格。

举例：

string name = "Mark";
var date = DateTime.Now;

// Composite formatting:
Console.WriteLine("Hello, {0}! Today is {1}, it's {2:HH:mm} now.", name, date.DayOfWeek, date);
// String interpolation:
Console.WriteLine($"Hello, {name}! Today is {date.DayOfWeek}, it's {date:HH:mm} now.");
// Both calls produce the same output that is similar to:
// Hello, Mark! Today is Wednesday, it's 19:40 now.

@ - 逐字字符串标识符

它具有以下用途：

下面的示例使用 @ 字符定义其在 for 循环中使用的名为 for 的标识符。

string[] @for = { "John", "James", "Joan", "Jamie" };
for (int ctr = 0; ctr < @for.Length; ctr++)
{
   Console.WriteLine($"Here is your gift, {@for[ctr]}!");
}
// The example displays the following output:
//     Here is your gift, John!
//     Here is your gift, James!
//     Here is your gift, Joan!
//     Here is your gift, Jamie!

2、这是原义字符串的较常见用法之一。

string filename1 = @"c:\documents\files\u0066.txt";
string filename2 = "c:\\documents\\files\\u0066.txt";

Console.WriteLine(filename1);
Console.WriteLine(filename2);
// The example displays the following output:
//     c:\documents\files\u0066.txt
//     c:\documents\files\u0066.txt

3、例如，由于编译器无法确定将 Info 还是 InfoAttribute 属性应用于 Example 类，因此下面的代码无法编译。

using System;

[AttributeUsage(AttributeTargets.Class)]
public class Info : Attribute
{
   private string information;

   public Info(string info)
   {
      information = info;
   }
}

[AttributeUsage(AttributeTargets.Method)]
public class InfoAttribute : Attribute
{
   private string information;

   public InfoAttribute(string info)
   {
      information = info;
   }
}

[Info("A simple executable.")] // Generates compiler error CS1614. Ambiguous Info and InfoAttribute.
// Prepend '@' to select 'Info'. Specify the full name 'InfoAttribute' to select it.
public class Example
{
   [InfoAttribute("The entry point.")]
   public static void Main()
   {
   }
}

【转载】：https://docs.microsoft.com/zh-cn/dotnet/csharp/language-reference/tokens/