best way to return an std::string that local to a function

Question

In C++ what is the best way to return a function local std::string variable from the function?

std::string MyFunc() {     std::string mystring("test");     return mystring;  }  std::string ret = MyFunc(); // ret has no value because mystring has already gone out of scope...??? 

Answer 1

No. That is not true. Even if mystring has gone out of scope and is destroyed, ret has a copy of mystring as the function MyFunc returns by value.

Answer 2

There will be a problem if your code is like:

std::string& MyFunc() {     std::string mystring("test");     return mystring; } 

So, the way you've written it is OK. Just one advice - if you can construct the string like this, I mean - you can do it in one row, it's sometimes better to do it like this:

std::string MyFunc() {     return "test"; } 

Or if it's more "complicated", for example:

std::string MyFunct( const std::string& s1,                      const std::string& s2,                      const char* szOtherString ) {     return std::string( "test1" ) + s1 + std::string( szOtherString ) + s2; } 

This will give a hint to your compiler to do more optimization, so it could do one less copy of your string (RVO).