Performance of pIter != cont.end() in for loop

Question

I was getting through \"Exceptional C++\" by Herb Sutter lately, and I have serious doubts about a particular recommendation he gives in Item 6 - Temporary Objects.

Answer 1

I've compiled the following slightly hacky code using g++ 4.7.2 with -O3 -std=c++11, and got identical assembly for both functions:

#include <list>
#include <string>

using namespace std;

struct Employee: public string { string addr; };

string FindAddr1(list<Employee> emps, string name)
{
  for (list<Employee>::const_iterator i = emps.begin(); i != emps.end(); i++)
  {
    if( *i == name )
    {
      return i->addr;
    }
  }
  return "";
}

string FindAddr2(list<Employee> emps, string name)
{
  list<Employee>::const_iterator end(emps.end());
  for (list<Employee>::const_iterator i = emps.begin(); i != end; i++)
  {
    if( *i == name )
    {
      return i->addr;
    }
  }
  return "";
}

In any event, I think the choice between the two versions should be primarily based on grounds of readability. Without profiling data, micro-optimizations like this to me look premature.