C/C++ sstream

ostringstream

#include 
#include 
#include 
using namespace std;

int main()
{
    ostringstream ostr1;
    ostr1 << "123" << endl;//     
    cout << ostr1.str();
    long curPos = ostr1.tellp(); //           ( put pointer  )
    cout << "curPos = " << curPos << endl;
    ostr1.seekp(4);     //   put pointer  
    ostr1.put('g');     //  put pointer      'g'，  put pointer         
    cout << ostr1.str() << endl;
    ostr1.clear();
    string ss = ostr1.str();
    const char *buffer = ss.c_str();
    cout << buffer << endl;
    return 0;
}