Question

I want to establish whether my understanding to some basic C++ reference principles are correct. To my understanding, declaring;

void foo(string &arg); //Means get the memory reference of passed argument
{
  cout << arg;        
}  

string arg;
string& arg1; //Means pass the memory reference of arg

Am I correct?

EDITED

Answer 1

string str;
string &arg1 = str; 
string& arg2 = str; 
string *ptr = &str;

Means arg1 & arg2 are references to a variable str which is of the type string, it means they are just an alias name for variable str.
They Both essentially declare a reference variable as said above it is just a matter of style where the & is placed.

ptr is a pointer to a variable str which is of the type string.

Note:
A reference must be initialized to a variable at the time of creation, and it cannot be made to refer any other variable after the initialization. A Reference always remains alias to the same variable. So you should not be just doing just:

string& arg2;

The compiler will give you an error for this, something like:

error: ‘arg2’ declared as reference but not initialized