Reverse a string

StringReverse.cc

#include <iostream>
#include <vector>

namespace String {
    std::string Reverse(std::string str) {
        char temp;
        for (unsigned long i = 0; 2*i < str.length(); ++i) {
            temp = str[i];
            str[i] = str[str.length()-i-1];
            str[str.length()-i-1] = temp;
        }
        return str;
    }

    std::string ReverseNoTemp(std::string str) {
        for (unsigned long i = 0; 2*i < str.length(); ++i) {
            str[i] ^= str[str.length()-i-1];
            str[str.length()-i-1] ^= str[i];
            str[i] ^= str[str.length()-i-1];
        }
        return str;
    }
};