SWIG: Warning 453: Can't apply (char *STRING,size_t LENGTH). No typemaps are defined

问题

I have a very small .i file basically with this information:

%module (directors="1") tu
%include "typemaps.i"
%include "enums.swg"

%header %{ 
#include <my_header.h>
%}

%apply (char *STRING, size_t LENGTH) { (char* msg_buf,  int buf_len) };

When generating java bindings there are no warnings but when generating c# bindings I get this:

SWIG: Warning 453: Can't apply (char *STRING,size_t LENGTH). No typemaps are defined

Can anyone advise on what might be the problem. The .i file is identical for java and c#.

来源：https://stackoverflow.com/questions/24012753/swig-warning-453-cant-apply-char-string-size-t-length-no-typemaps-are-def