VC2015编写的DLL给其他语言调用

(1)用C++builder6调用DLL

用VC2015创建包含MFC库的DLL,如果是给C++Builder6使用，步骤如下:
1、工程属性==》C++==》高级==》调用约定 选项为：__stdcall (/Gd)

2、VC++2015中的函数声明如下：
extern "C" __declspec(dllexport) VOID __stdcall CreateMeter(const char* szTypeName);

3.VC++2015的def文件,EXPORTS可以不用写，因为C++Builder6不用到这个.lib文件
不过,我发现要导出函数,需要在def字声明,否则在其他语言中找不到函数,提示错误.

4.在C++Builder6中,需要重新导出DLL的引导库.lib，方法如下：
implib my.lib my.dll

在BCB6工程中引入my.lib，同时添加函数声明，也就是VC2015DLL中的函数声明(与第2步相同)

(2)用Delphi7调用

unit ScaleWeight_dll;interface       procedure  CreateMeter(xktype:PChar;       No:integer;       Comm:integer;       baud:integer;       parity:Char;       databit:integer;       stopbit:integer       );stdcall;external 'YuComm.dll';       //获取重量字符串       function  GetWeight( buff :pchar;index :integer = 1):PChar;stdcall;       external 'YuComm.dll';       //写串口       procedure WritePort( buff :array of byte;index :integer = 0);stdcall;       external 'YuComm.dll';       function ClosePort(index :integer=1):integer;stdcall;external 'YuComm.dll';       //name 'ClosePort1';       //辅助函数       //缓取缓冲区数据量       function GetBuffLength(index :integer =0):integer;stdcall;       external 'YuComm.dll';       //或取通信状态；true串口打开但通信中断，false通信正常       function GetStatus(index :integer =0):boolean;stdcall;external 'YuComm.dll';       //清除缓冲区数据       //procedure Clear(index :integer =0);stdcall;external 'YuComm.dll';       //获取原始数据       function  GetSourceData( buff :pbyte;index :integer = 0):integer;stdcall;       external 'YuComm.dll';       implementationend.

将上面文件保存为扩展名为pas的文件,添加到delphi7工程中.

(3)在VB6中调用DLL

Private Declare Function CreateMeter Lib "YuComm"(ByVal name As String, _ByVal No As Integer, _ByVal port As Integer, _ByVal baud As Integer, _ByVal parity As Integer, _ByVal databit As Integer, _ByVal stopbit As Integer) As Boolean'需要添加一个返回值声明,即使不需要Private Declare Function GetWeight Lib "YuComm"(ByVal buff As String, Optional ByVal index As Integer = 1) As LongPrivate Declare Function GetStatus Lib "YuComm"(Optional ByVal index As Integer = 1) As IntegerPrivate Declare Function ClosePort Lib "YuComm"(Optional ByVal index As Integer = 1) As Boolean Private Sub Command1_Click()  Dim name As String  Dim port As Integer  Dim baud As Integer    name = Combo1.Text  port = CInt(Text1.Text)  baud = CInt(Text2.Text)  CreateMeter name, 1, port, baud, 110, 8, 1  End SubPrivate Sub Command2_Click()  ClosePort (1)End SubPrivate Sub Command3_Click()End SubPrivate Sub Timer1_Timer()   Dim re As Boolean      re = GetStatus(1)   If re = True Then     Label2.Caption = "串口打开成功"   Else     Label2.Caption = "串口打不成功"   End If      Dim buff1  As String   buff1 = Space(100)   Call GetWeight(buff1, 1)   Label1.Caption = buff1   End Sub

在XP平台下,用VB6调用,请用release方式编译,否则VB6会提示找不到相应的DLL文件,即所这个文件就在运行目录下

在VB中调用,声明函数时应加上返回值,即使DLL中这个函数没有返回值.返回值的类型可任意

(4)在C#中调用DLL

public partial class Form1 : Form    {        //========================================================================        //1、创建仪表，并打开仪        [DllImport("YuComm.dll")]        public static extern bool CreateMeter(string xktype,int no,int comm,        int baud,int parity,int databit,int stopbit);        //2、读取仪表重量，多台仪表时，参数为索引        [DllImport("YuComm.dll")]        public static extern string GetWeight(StringBuilder weight, int index = 1);        //写串口        [DllImport("YuComm.dll")]        public static extern void Write(ref byte buff,int index = 1);        //3、关闭串口        [DllImport("YuComm.dll")]        public static extern void ClosePort( int index=1);            //ScaleWeight辅助功能函数：获取缓冲区数据个数        [DllImport("YuComm.dll")]        public static extern int GetBuffLength(int index = 1);        //获取通信状态：false通信正常 ，true通信中断        [DllImport("YuComm.dll")]        public static extern bool GetStatus(int index=1);        //辅助功能函数：读取原始数据流        [DllImport("YuComm.dll")]        public static extern int GetSourceData(ref byte buff, int index = 1);        //辅助功能函数：清除缓冲区        //[DllImport("YuComm.dll")]        //public static extern void Clear(int index=1);       //===================================================================        public Form1()        {            InitializeComponent();        }        private void button1_Click(object sender, EventArgs e)        {           xktype  = comboBox1.Text;           szComm    = textBox1.Text;           szBaud = textBox2.Text;           bool re = CreateMeter(xktype, 1, Convert.ToInt32(szComm),            Convert.ToInt32(szBaud), 'n', 8, 1);           if (re)           {               label1.Text = "串口状态：打开成功";           }           else           {               label1.Text = "串口状态：打开不成功";           }        }        private void button2_Click(object sender, EventArgs e)        {            ClosePort(1);            label1.Text = "串口状态：串口关闭";        }        private void timer1_Tick(object sender, EventArgs e)        {            StringBuilder buff = new StringBuilder(255);             GetWeight(buff,1);            label2.Text = buff.ToString();            buff = null;//释放            label5.Text = "缓冲区中数据量："+ GetBuffLength().ToString();            bool re = GetStatus();            if (re)                label4.Text = "通信状态：通信数据流正常";            else                label4.Text = "通信状态：通信数据流中断";            byte[] data = new byte[1024];            int c = GetSourceData(ref data[0],1);            richTextBox1.Clear();            for (int i = 0; i < c; i++)            {                richTextBox1.Text += data[i].ToString("X2") +" ";            }            data = null;        }        private void button3_Click(object sender, EventArgs e)        {            byte[] buff = new byte[1024];            string a = "hello";            BitConverter.ToString(buff);            Write(ref buff[0], 1);            buff = null;        }        private void button4_Click(object sender, EventArgs e)        {            timer1.Enabled = !timer1.Enabled;            if (timer1.Enabled)                button4.Text = "暂停";            else                button4.Text = "开始";        }    }

在XP上运行,请使用release方式编译发布,否则调用DLL中的函数时会报错!