範例7-1－Quality of life is not what you get but what you become

//---------------------------------------------------------------------------
#include <iostream>
//---------------------------------------------------------------------------
int result; // 計算的結果
char oper_char; // 使用者指定的運算子
int value; // 在運算子後面的數值

int main(int argc, char* argv[])
{
result = 0; //設定結果的初值

        //無窮迴圈(遇到break敘述才停止)
        while (true){
          std::cout << " Result: " << result <<'\n';

std::cout << " Enter operator and number: ";
std::cin >> oper_char >> value;

          if (oper_char = '+') {
            result += value;
          } else {
              std::cout << " Unknown operator " << oper_char << '\n';
          }
        }
        std::system("pause");
        return 0;
}
//---------------------------------------------------------------------------

題目來源：C++風格與藝術第二版 Steve Oualline 著黃吉霈編譯