Was this page helpful?
Your feedback about this content is important. Let us know what you think.
Additional feedback?
1500 characters remaining
Export (0) Print
Expand All
Expand Minimize

Compiler Error C3642

'return_type/args' : cannot call a function with __clrcall calling convention from native code

A function that is marked with the __clrcall calling convention cannot be called from native (unmanaged) code.

return_type/args is either the name of the function or the type of the __clrcall function you are trying to call. A type is used when you're calling through a function-pointer.

To call a managed function from a native context, you can add a "wrapper" function that will call the __clrcall function. Or, you can use the CLR marshalling mechanism; see How to: Marshal Function Pointers Using PInvoke for more information.

The following sample generates C3642:

// C3642.cpp
// compile with: /clr
using namespace System;
struct S {
   void Test(String ^ s) {   // CLR type in signature, implicitly __clrcall
   void Test2(char * s) {
      Test(gcnew String(s));

#pragma unmanaged
int main() {
   S s;
   s.Test("abc");   // C3642
   s.Test2("abc");   // OK
© 2015 Microsoft