Midterm 2 Question

[Robert]

I have a question about the midterm. The ip addresses consisted 12
bits, we were required to stored these numbers into the Hash table.
How do we do that? I got stuck on this part. I could not convert a
string (read from a file) to an unsigned long long.

[Konstantin Vyshetsky]

We were actually storing the last 6 numbers of the ip address or half of the IP address, this would make it 16 bits.

Since I read the whole number as an 8 byte unsigned long, to get the last 6 numbers I took mod 1,000,000, and then modded the result with the size of the hash table.
To convert a number into a string, use sstream:

stringstream ss;

ss << number;

string numberString = ss.str();

To convert a string into a number:

string numberString;

istringstream(numberString) >> number;

- Kon

[Robert Wang]

Thanks, I tested and it worked.  This was the code I was looking for:


    unsigned long long number;

    string numberString = "234201157163";
    istringstream(numberString) >> number;   

    cout << number << endl;