CallingConvention Enum
Definition
Important
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Specifies the calling convention required to call methods implemented in unmanaged code.
public enum class CallingConvention
public enum CallingConvention
[System.Serializable]
public enum CallingConvention
[System.Serializable]
[System.Runtime.InteropServices.ComVisible(true)]
public enum CallingConvention
type CallingConvention =
[<System.Serializable>]
type CallingConvention =
[<System.Serializable>]
[<System.Runtime.InteropServices.ComVisible(true)>]
type CallingConvention =
Public Enum CallingConvention
- Inheritance
- Attributes
Fields
Cdecl | 2 | The caller cleans the stack. This enables calling functions with |
FastCall | 5 | This calling convention is not supported. |
StdCall | 3 | The callee cleans the stack. |
ThisCall | 4 | The first parameter is the |
Winapi | 1 | This member is not actually a calling convention, but instead uses the default platform calling convention. |
Examples
The following example demonstrates how to apply the Cdecl
calling convention, which you must use because the stack is cleaned up by the caller.
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
Remarks
Always use the CallingConvention enumeration rather than the CALLCONV enumeration to specify a calling convention in managed code. The latter exists only for the sake of COM definitions. The CallingConvention enumeration is used by DllImportAttribute and several classes in System.Reflection.Emit to dynamically emit platform invoke signatures.