Function pointer for socket io functions send() and recv()

Question

So I have a function called sockio() that takes a function pointer for either the send() or recv() functions in Winsock 1.1 but I get an error when I try to pass either as an argument of my function pointer type iofunc, defined below.

I can't seem to make them match up so that it'll let me pass in send() or recv(), why is this?

// my function pointer typedef
typedef int (*iofunc)(SOCKET, const char*, size_t, int); 

// sockio function prototype
static int sockio(int socket, sockio_buf* buf, iofunc io);

Heres the error it gives me when I try to compile in Visual C++ 2010:

1>c:\...\sockio.c(24): error C2440: 'function':
  cannot convert from 'int (__stdcall *)(SOCKET,const char *,int,int)' to 'iofunc'
1>c:\...\sockio.c(24):
  warning C4024: 'sockio': different types for formal and actual parameter 3

All the parameters look the same to me. Is it anything to do with the (__stdcall *) bit?

I don't know whether that's the only problem, but yes, the function pointer will need to be declared as stdcall. — Harry Johnston, Aug 29 '14 at 11:44
Yup, that fixed it, thanks Harry Used this: http://stackoverflow.com/questions/5298394/how-to-declare-an-stdcall-function-pointer — ethrzael, Aug 29 '14 at 12:18

score 0 · Accepted Answer · answered Aug 29 '14 at 19:19

0

Your typedef is missing a calling convention, so C's default calling convention (usually __cdecl) is used instead. send() and recv() use the __stdcall calling convention:

typedef int (__stdcall *iofunc)(SOCKET, const char*, size_t, int);

answered Aug 29 '14 at 19:19

Remy Lebeau

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Function pointer for socket io functions send() and recv()

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