Solution: Reverse a String

Naive

reverse-string-naive.cpp

#include <string>
#include <iostream>

using namespace std;



int main()
{
    string s;
    cin >> s;

    string reversed_s;

    for (int i=s.size()-1; i>=0; i--)
        reversed_s += s[i];

    cout << reversed_s << endl;

    return 0;
}

Using std::reverse<>

See reverse<>: Reversing In-Place

reverse-string-reverse.cpp

#include <string>
#include <iostream>
#include <algorithm>

using namespace std;


int main()
{
    string s;
    cin >> s;

    std::reverse(s.begin(), s.end());

    cout << s << endl;

    return 0;
}

Using std::reverse_copy<>

See reverse_copy<>: Copying and Reversing

reverse-string-reverse-copy.cpp

#include <string>
#include <iostream>
#include <algorithm>

using namespace std;


int main()
{
    string s("abc");

    string reversed_s(s.size(), '*');
    std::reverse_copy(s.cbegin(), s.cend(), reversed_s.begin());
    cout << reversed_s << endl;

    return 0;
}