C#中$的用法:是爲了替代string.format();原先賦值須要佔位符和變量,當須要拼接多個變量會形成語句過長等不易理解問題,$""是爲了替代string.format(),能夠把字符串中的C#變量{}包含起來達到識別C#變量的目的$"{id}";也支持表達式,使用$"{(你的表達式)}"spa
var k = "a"; var a0 = "User"; var a1 = "Id"; var a2 = 5; var ccc = string.Format("select * from {0} where {1} = {2}", a0, a1, a2); var ccb = $"select * from {a0} where {a1}={a2}";
固然也支持string.format()裏面的格式,如:code
var k = "a"; var k4 = $"{k,5}"; var k3 = string.Format("{0,5}", k); var k2 = DateTime.Now; var c = $"{k2:yyyy}"; c = string.Format("{0:yyyy}", k2);