Difference between revisions of "cpp/string/basic string/rbegin"

#include <iostream>
#include <algorithm>
#include <iterator>
#include <string>
 
int main()
{
    std::string s("Exemplar!");
    *s.rbegin() = 'y';
    std::cout << s << '\n'; // "Exemplary"
 
    std::string c;
    std::copy(s.crbegin(), s.crend(), std::back_inserter(c));
    std::cout << c << '\n'; // "yralpmexE"
}

#include <iostream>
#include <string>
#include <cassert>
#include <stdexcept>
 
 
using std::cout;
using std::cin;
using std::endl;
using std::cerr;
 
/// std::basic_string::rbegin, std::basic_string::crbegin
/*
 
reverse_iterator rbegin();
 
const_reverse_iterator rbegin() const;
 
const_reverse_iterator crbegin() const; (since C++11)
 
*/
 /// Return value : reverse iterator to the first character
 
 
int main (int ac,char **av, char **lvs) {
    { /// test reverse_iterator re begin()
        cout<<"test reverse_iterator re begin()"<<endl;
 
        std::basic_string<char> s ("a b c d e f g h");
 
        cout<<"Before using iterator : "<<s<<endl;
 
        *s.rbegin() = 'H'; /// changing 'h' to 'H'
 
        cout<<"After using iterator : "<<s<<endl;
 
    }
    { /// continuing test above
 
        std::basic_string<char> s ("a b c d e f g h");
 
        std::basic_string<char>::reverse_iterator ris = s.rbegin();
 
        cout<<*ris<<endl;
 
        while(*ris){
 
            cout<<*ris<<' ';
 
            ++ris;
        }
        ris-=s.size(); /// Okay
 
        auto bris = (ris); /// Okay
 
        cout<<endl<<*bris<<endl;
    }
    { /// Test const_reverse_iterator rbegin() const;
 
        cout<<"Test const_reverse_iterator rbegin() const;"<<endl;
 
        std::string s ("1 2 3 4 5 6 7 8 9");
 
        cout<<"Before : "<<s<<endl;
 
        std::string::const_reverse_iterator cris = s.rbegin();
 
        cout<<*cris<<endl; /// Output -> 9
 
        for( ; *cris ; ++cris )
            cout<<*cris<<' '; /// Output -> 9 8 7 6 5 4 3 2 2 1
 
        cris-= s.size(); /// Reset Address to rbegin
        /*
        *cris = '*' /// error: assignment of read-only location cris...
 
        for( ; *cris ; ++cris )
            cout<<*cris<<' ';
        */
        cout<<endl;
    }
    { /// Test const_reverse_iterator crbegin() const; (since C++11)
 
        cout<<"Test const_reverse_iterator crbegin() const; (since C++11)"<<endl;
 
        std::string s ("A B C D E F G H");
 
        std::string::const_reverse_iterator cris = s.crbegin();
 
        cout<<*cris<<endl;
        /*
        *cris = '*' /// error: assignment of read-only location cris...
 
        for( ; *cris ; ++cris )
            cout<<*cris<<' ';
        */
        while (*cris) {
            cout<<*cris<<' ';
            ++cris;
        }
 
    }
 
}