I find a piece of code like this
int a = 100;
string str = $"{a:0.00}";
Console.WriteLine(str);
the result is "100.00"
The $ have the same function of string.Format, and I want to know which version of C#.
This is called string interpolation, and it's part of C# 6, which was released in July as part of Visual Studio 2015.