#include <string>
using namespace std;

string& trim_str(string& s);
string& trim_str(string& s)
{
	return s.erase(s.find_last_not_of(" ")+ 1 );
}

int main()
{
	string s;
	while(getline(cin, s) && !s.empty())
	{
		cout << "source: \"" << s << "\"\n";
		cout << "trimmed: \"" << trim_str(s) << "\"\n";
	}
	return  0 ;
}

 basic_string::substr

CString::Left

string& trim_str(string& s);
string& trim_str(string& s)
{
	return s.erase(s.find_last_not_of(" ")+ 1 );
}

#include <iostream>

using namespace std;

class C
{
public:
	C() {cout << "C::ctor this = " << this << endl;}
	C(const C& c) {cout << "C::cctor this = " << this << endl;}
	~C() {cout << "dtor" << endl;}

	C& dummy()
	{
		cout << "C::dummy. this = " << this << endl;
		return *this;
	}
};

C& f_ref(C& ref)
{
	return ref.dummy();
}

C& f_val(C val)
{
	return val.dummy();
}

int main()
{
	{
		cout << "reference test" << endl;
		C c;
		f_ref(c);
		
	}
	
	{
		cout << endl << "value test" << endl;
		C c;
		f_val(c);
	}
	
	return  0 ;
}

f_ref(c).dummy();

...

f_val(c).dummy();