c# - 'System.Collections.Generic.List' does not contain a definition for ' Sum'

Question

我正在尝试使用内置的 Sum() 函数对 float 列表求和，但我不断收到此错误:

Error CS1061: 'System.Collections.Generic.List' does not contain a definition for 'Sum' and no extension method 'Sum' accepting a first argument of type 'System.Collections.Generic.List' could be found (are you missing a using directive or an assembly reference?) (CS1061)

我有

using System.Collections;
using System.Collections.Generic;

在文件的开头:

代码:

List<float> x = new List<float>();
x.add(5.0f);
//..
float f = x.Sum();

Answer 1

您需要添加到您的using 指令:

using System.Linq;

此外，您的代码在语法上是错误的。这是工作版本:

var x = new List<float>();
x.Add(5.0f);
var f = x.Sum();