goto

include

using namespace std;

int main()
{

int x, sum = 0;
//定义标号L1
L1:	cout << "x=";
cin >> x;
if (x == -1)
	goto L2;//无条件转移语句，转到L2语句处
else
	sum += x;
goto L1; //无条件转移语句，转到L1语句处
//定义标号L2
L2:	cout << "sum =" << sum << endl;
return 0;

}