DOUBLE PRECISION FUNCTION ADD(A,B)
!DEC$ ATTRIBUTES DLLEXPORT::ADD
!DEC$ ATTRIBUTES STDCALL,ALIAS:'Add'::ADD
    DOUBLE PRECISION:: A,B
    ADD=A+B
END

FUNCTION SORTANDFINDMAX(ARRAY,LENGTH)
!DEC$ ATTRIBUTES DLLEXPORT::SORTANDFINDMAX
!DEC$ ATTRIBUTES STDCALL,ALIAS:'Sortandfindmax'::SORTANDFINDMAX
DOUBLE PRECISION ::ARRAY(LENGTH)
INTEGER::I,J
DOUBLE PRECISION::SORTANDFINDMAX,TEMP
SORTANDFINDMAX=ARRAY(1)
DO I=1,LENGTH-1
    DO J=I+1,LENGTH
        IF(ARRAY(I).GT.ARRAY(J)) THEN
            TEMP=ARRAY(I)
            ARRAY(I)=ARRAY(J)
            ARRAY(J)=TEMP
            SORTANDFINDMAX=ARRAY(J)
            END IF
    END DO
    END DO
END

DOUBLE PRECISION FUNCTION ADD(A, B)

!DEC$ ATTRIBUTES DLLEXPORT:: ADD

DOUBLE PRECISION A,B  

ADD =A+B

END

[DllImport("MathDll")]

private static extern double ADD (double A, double B);

Double Precision Function ADD (A, B)

!DEC$ ATTRIBUTES DLLEXPORT:: ADD

!DEC$ ATTRIBUTES ALIAS:'Add' :: Add

Double Precision A,B  

Add =A+B

End

[DllImport("MathDll")]

private static extern double Add (double A, double B);

Double Precision Function ADD(A, B)

!DEC$ ATTRIBUTES DLLEXPORT:: ADD

DOUBLE PRECISION A,B  

ADD =A+B

END

[DllImport("MathDll",EntryPoint = " ADD ")]

private static extern double Plus(double A, double B);

!DEC$ ATTRIBUTES STDCALL ::Object

!DEC$ ATTRIBUTES C :: Object

[DllImport("FileName.dll", CallingConvention = CallingConvention.StdCall)]

[DllImport("FileName.dll", CallingConvention = CallingConvention.Cdecl)]

using System;
using System.Text;
using System.Runtime.InteropServices;

namespace MixedProgram
{
   public static class FortranMethod
    {
       [DllImport("TestDll.dll",CallingConvention = CallingConvention.Cdecl)]
       public static extern double Add(double a, double b);

       [DllImport("TestDll.dll", CallingConvention = CallingConvention.Cdecl)]
       public static extern double Sortandfindmax(double[] array, int length);
    }
}

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

namespace MixedProgram
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("请输入两个数相加：");
            double num1=Convert.ToDouble(Console.ReadLine());

            double num2 = Convert.ToDouble(Console.ReadLine());
            Console.WriteLine("输入的两个数是：" + num1 + " ," + num2);
            double sum = FortranMethod.Add(num1,num2);
            Console.WriteLine("求和结果是："+sum);

            double[] Array = { 1,5,2,4,3,7,6};
            Console.WriteLine("初始数组：");
            for (int i = 0; i < Array.Length; i++)
                Console.Write(Array[i]+" ");

            double b=FortranMethod.Sortandfindmax(Array, Array.Length);
            Console.WriteLine("\n"+"排序后：");

            for (int i = 0; i < Array.Length; i++)
                Console.Write(Array[i]+" ");

            Console.WriteLine("\n"+"最大值为：");
            Console.WriteLine(b);

            Console.ReadKey();
        }
    }
}