CallingConvention 枚举

定义

命名空间:

System.Runtime.InteropServices

程序集:

System.Runtime.InteropServices.dll

指定调用在非托管代码中实现的方法所需的调用约定。

public enum class CallingConvention

public enum CallingConvention

type CallingConvention = 

Public Enum CallingConvention

继承

Object

ValueType

Enum

CallingConvention

字段

Cdecl	2	调用方清理堆栈。 这使你能够调用具有 varargs 的函数（如 Printf），使之可用于接受可变数目的参数的方法。
FastCall	5	不支持此调用约定。
StdCall	3	被调用方清理堆栈。
ThisCall	4	第一个参数是 this 指针，它存储在寄存器 ECX 中。 其他参数被推送到堆栈上。 此调用约定用于对从非托管 DLL 导出的类调用方法。
Winapi	1	此成员实际上不是调用约定，而是使用 默认的平台调用约定。

示例

以下示例演示如何应用 Cdecl 调用约定，由于堆栈由调用方清理，因此必须使用该约定。

using namespace System;
using namespace System::Runtime::InteropServices;

private ref class NativeMethods
{
public:

    // CallingConvention.Cdecl must be used since the stack is 
    // cleaned up by the caller.
    // int printf( const char *format [, argument]... )

    [DllImport("msvcrt.dll", CharSet = CharSet::Unicode, CallingConvention = CallingConvention::Cdecl)]
    static int printf(String^ format, int i, double d);

    [DllImport("msvcrt.dll", CharSet = CharSet::Unicode, CallingConvention = CallingConvention::Cdecl)]
    static int printf(String^ format, int i, String^ s);
};

int main()
{
    NativeMethods::printf("\nPrint params: %i %f", 99, 99.99);
    NativeMethods::printf("\nPrint params: %i %s", 99, "abcd");
}

using System;
using System.Runtime.InteropServices;

internal static class NativeMethods
{
    // C# doesn't support varargs so all arguments must be explicitly defined.
    // CallingConvention.Cdecl must be used since the stack is
    // cleaned up by the caller.

    // int printf( const char *format [, argument]... )

    [DllImport("msvcrt.dll", CharSet = CharSet.Unicode, CallingConvention = CallingConvention.Cdecl)]
    internal static extern int printf(String format, int i, double d);

    [DllImport("msvcrt.dll", CharSet = CharSet.Unicode, CallingConvention = CallingConvention.Cdecl)]
    internal static extern int printf(String format, int i, String s);
}

public class App
{
    public static void Main()
    {
        NativeMethods.printf("\nPrint params: %i %f", 99, 99.99);
        NativeMethods.printf("\nPrint params: %i %s", 99, "abcd");
    }
}

Imports System.Runtime.InteropServices

Friend Class NativeMethods
    ' Visual Basic does not support varargs, so all arguments must be 
    ' explicitly defined. CallingConvention.Cdecl must be used since the stack 
    ' is cleaned up by the caller. 
    ' int printf( const char *format [, argument]... )

    <DllImport("msvcrt.dll", CharSet:=CharSet.Unicode, CallingConvention:=CallingConvention.Cdecl)>
    Friend Overloads Shared Function printf(
        ByVal format As String, ByVal i As Integer, ByVal d As Double) As Integer
    End Function

    <DllImport("msvcrt.dll", CharSet:=CharSet.Unicode, CallingConvention:=CallingConvention.Cdecl)>
    Friend Overloads Shared Function printf(
        ByVal format As String, ByVal i As Integer, ByVal s As String) As Integer
    End Function
End Class

Public Class App
    Public Shared Sub Main()
        NativeMethods.printf(ControlChars.CrLf + "Print params: %i %f", 99, 99.99)
        NativeMethods.printf(ControlChars.CrLf + "Print params: %i %s", 99, "abcd")
    End Sub
End Class

注解

始终使用 CallingConvention 枚举而不是 CALLCONV 枚举在托管代码中指定调用约定。 后者仅用于 COM 定义。 枚举 CallingConvention 由 DllImportAttribute 和 中的 System.Reflection.Emit 多个类用于动态发出平台调用签名。

另请参阅

• DllImportAttribute
• System.Reflection.Emit