[C++Primer]練習1.9

#include 

using std::cin;
using std::cout;
using std::endl;

int main() {
    int start = 50, sum = 0;
    while (start <= 100) {
        sum += start;
        ++start;
    }
    cout << "sum of 50 to 100 inclusive is " << sum << endl;
}