std::string c_str() scope after returning from function

Question

I have below mentioned function in C++/MFC:

CString StringFunc()
{
    std::string abc = "Hello";

    return abc.c_str();

}

int main()
{
    CString Temp = StringFunc();

    Use_Temp(Temp);
}

1.) What would be the lifetime of abc.c_str() pointer returned by StringFunc(), would it be safely copied to variable 'Temp' after StringFunc() returns ?

2.) CString Temp = StringFunc() is a Shallow copy operation or Deep Copying ?

Answer 1

What would be the lifetime of abc.c_str() pointer returned by StringFunc(), would it be safely copied to variable 'Temp' after StringFunc() returns ?

abc will be valid until StringFunc() function returns. Yes, it's safe to return a copy to CString.

If you return a pointer to std::string::c_str() then it's dangerous, for example:

const char* EvilFunc()  // bad, dont' do it
{
   std::string abc = "Hello";
   return abc.c_str();
}

const char* p = EvilFunc(); // p becomes wild pointer when EvilFunc returns

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CString Temp = StringFunc() is a Shallow copy operation or Deep Copying ?

It's deep copy. it constructs a new CString object from const char*