Question about references in C++ and GCC Topic is solved

[maxinuruguay]

I'm having a little problem with porting my code over to Xcode (GCC) from Visual Studio. I'm still don't understand C++ fully so bear with me. Consider this code:

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m_object->AppendCustomValue(event.GetString())

event.GetString() returns a wxString object (not a reference or pointer)
AppendCustomValue is defined as AppendCustomValue(wxString&)

Xcode pops up an error saying there is no matching function for the call AppendCustomValue(wxString) and that the likely candidate is AppendCustomValue(wxString&)

Apparently, GCC differs from the Visual Studio compiler in that the MSW compiler will auto convert a returned object into a reference and GCC will not. Is this correct?

My workaround code is

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wxString st;
st = event.GetString();
wxString& temp = st;
m_object->AppendCustomValue(temp);

Kind of a pain. Is this how it's done? Thanks.

[rjmyst3]

If you change

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AppendCustomValue(wxString&)

to

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AppendCustomValue(const wxString&)

then this

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m_object->AppendCustomValue(event.GetString())

will work.

Here's why:
When you pass the result of event.GetString() to AppendCustomValue(), it is only ever a temporary object. The C++ standard does not allow a reference to nowhere. A const reference will keep the temporary object alive until the the const reference goes out of scope.

That is why it works to pass a temporary into a const reference, but it does not work to pass a temporary into a non-const reference.