need help about "how to use strstream"!

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C++

I want "172" in buffer[3] but now it is "1".and i want "." in dot. can you tell me how to do?

#include <stdio.h>
#include <tchar.h>
#include <strstream>
using namespace std;
int _tmain(int argc, _TCHAR* argv[])
{
    char dot;
    char buffer[4];
    strstream strs;
    strs << "172.24.41.40";
    strs >> buffer[3]>>dot>>buffer[2]>>dot>>buffer[1]>>dot>>buffer[0];
    printf("%d",*((int*)buffer));
    return 0;
}

i just want to use strstream.