c++ passing a string literal instead of a const std::string&?

Question

I have the following code which compiles with no warnings (-Wall -pedantic) with g++

#include 
#include 

using namespace std;

cla         


        

Answer 1

The reason why this fails is because it essentially compiles to the following under the hood.

Foo o(std::string("wurd"));

In this case the Foo value is taking a reference to a temporary object which is deleted after the constructor completes. Hence it's holding onto a dead value. The second version works because it's holding a reference to a local which has a greater lifetime than the Foo instance.

To fix this change the memebr from being a const std::string& to a const std::string.