C++ ostringstream问题

Question

include <iostream>

include <sstream>

using namespace std;
int main()
{

ostringstream ostr("abcd");
ostr.put('1');
cout<<ostr.str();
cout<<endl;

ostr<<"hi";
ostr.put('56');  ///这边为何不是输出1bc56 而是1bc6?
cout<<ostr.str();

}

Answer 1

ostringstream对象的put操作参数为char类型。参考

Answer 2

本质相当于
put((char)'56')