字符串倒序

将 I am Beijing. 倒序为Beijing. like I 

用栈实现:

#include <iostream>
#include <stack>
#include <string>
using namespace std;
int main()
{
    string str = "I like Beijing.";
    str = ' ' + str;
    string newStr = "";
    stack<char> st;
    for (int i = str.length() - 1; i >= 0; i--)
    {
        char c = str.at(i);
        if (c !=' '  )
        {
            st.push(c);
        }
        else {
            string temp = "";
            while (!st.empty())
            {
                temp += st.top();
                st.pop();
            }
            newStr += temp  + ' ';
        }
    }
    cout<<newStr<<endl;
}