1) getpath() return a temp string, its c_str() pointer will be free
out of function. So I use malloc
2) Assume we use the malloc way , are C.GoString() copying the pointer
memory ? for we need C.free() malloc memory.
2017-04-19 14:17 GMT+08:00 Konstantin Khomoutov <
flatw...@users.sourceforge.net>:
> On Tue, 18 Apr 2017 18:09:03 -0700 (PDT)
> hui zhang <fastfad...@gmail.com> wrote:
>
> > > > c code
> > > > string getstring() {...}
> > > > go
> > > > string gostr = ????(C.getstring())
> > > Oh, and note that std::string is a fat object.
> > >
> > > So if getstring() really returns an instance of std::string,
> > > and you need to actually extract its "raw bytes", you'd need to
> > > call the c_str() method of std::string on that object before
> > > applying the techniques from [1] to it.
> > >
> > > 1. https://github.com/golang/go/wiki/cgo#go-strings-and-c-strings
> > >
> > assume there is a c++ function string getpath()
> > you mean I should do this ?
> >
> > char *CGetPath() {
> > > auto str=getpath;
> > > char *c = malloc(str.length()),
> > > strcpy(c,str.c_str());
> > > return c;
> > > }
>
> I beleive there's no need to do malloc() and copy the bytes over:
> c_str () is defined to return to you a pointer to a contiguous array of
> NUL-terminated representation of the string maintained by the
> std::string instance. So you do (untested):
>
> char *CGetPath() {
> return getpath().c_str();
> }
>
> and then in your Go code you do
>
> p := C.GoString(C.GetPath())
>
> 2. http://en.cppreference.com/w/cpp/string/basic_string/c_str
>
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