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类库的引用

还可以自己引用类库：解决方案-添加-新建项目

主程序

using System;
using System.Windows.Forms;
using Tools;namespace ConsoleApp2
{class Program{static void Main(string[] args){//Console.WriteLine("helloword");// Form form = new Form();// form.ShowDialog();double result = Calculator.Mul(3, 4);Console.WriteLine(result);}}
}

在引用里添加自己创建的类库

类库程序

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace Tools
{public class Calculator{public static double Add(double a, double b){return a + b;}public static double Sub(double a, double b){return a - b;}public static double Mul (double a, double b){return a * b;}public static double Div(double a, double b){if (b == 0){return double.PositiveInfinity;}else{return a / b;}}}
}