运行下面的代码，屏幕上将输出（ ）。
#include <iostream>using namespace std; int divide(int a, int b) { if (b == 0) { throw runtime_error("division by zero error "); } return a / b;} int main() { int x = 10; int y = 0; // 设为 0 会导致除零错误 try { int result = divide(x, y); cout << "result: " << result << endl; } catch (const runtime_error& e) { cout << "caught an exception: " << e.what() << endl; } return 0;}