How are addresses of objects created on the stack temporary

Question

I came across this question and I would like to know why the address of a non constant string created on the stack of a method returns a constant pointer when its address is requested. I have copy-pasted the code sample used there

void myfunc(string*& val)
{
    // Do stuff to the string pointer
}

int main()
{
    // ...
    string s;
    myfunc(&s);
    // ...
} 

My question is that & returns the address of a variable. So In the above case the std::string s is a non constant then why is it returning its address as a constant ? What I want to know is why the address of the non-constant string is returned as a constant address. Are the addresses of all objects created on the stack constant ?

Answer 1

Let's say you did:

void myfunc(string*& val)
{
    val = NULL;
    // How is that supposed to affect the variable s in main?
    // You can't change the address of the object in main.
    // Once a variable is created, its address cannot be modified.
}

int main()
{
    // ...
    string s;

    // Since the address of s cannot be changed,
    // the type of &s is "string* const" not "string&".

    // That's why the call to myfunc is wrong.
    myfunc(&s);
}