这里引用了一个新的库，叫#include “sstream”。
可以同时转换不同类型

#include <iostream>
#include <string>
#include <sstream>using namespace std;string s;
string answer = "";
//3,3,4,2,10,3,4,7
//3,3,4,2,10,3,4,7,5
/*
She was born in 1990-01-02  and  from Beijing city.
*/string int2str(int aNum)
{stringstream res;res << aNum;string s;res >> s;return s;
}int main()
{getline(cin, s);int length = s.size();int sum = 0;for(int i = 0; i < length; i++){if(s[i] == ' '){if(sum != 0){answer += int2str(sum) + ",";sum = 0;}elsesum = 0;}elsesum++;}answer += int2str(sum) + ",";int ansl = answer.size();for(int i = 0; i < ansl - 1; i++)cout << answer[i];cout << endl;return 0;
}