Question

can any one tell me .Is there any benefit of passing string as func(string& ) instead of func( string).

Answer 1

Passing an object by reference means, well, that you’re passing the reference by value, instead of passing the object by value, which means that you have to made a copy at function invocation.

However, passing-by-reference introduces a new set of questions which you must be aware of:

1. does the function modifies or not the passed object? If it does not, you should put in the const modifier
2. does the function need to modify the object, but not exposing the modifications outside the function boundaries? In that case what you really want is a copy.
3. does the function stores somewhere/somehow the reference of the passed object? In that case, you have to understand how object ownership is passed and when it’s safe to delete it. You may want to use smart pointers to deal with these issues

The point is: just because passing-by-reference makes function invocation cheaper does not means that you must use it in any case.