Xcode下输入vector1回车或者ctrl+D就return 0 ，无法输入vector2 ，语句中cin.clear()好像没起到作用？

Question

#include
#include

using namespace std;

int main() {

vector<int> ivec1, ivec2;
int ival1, ival2;

cout << "enter numbers for vector 1 : " << endl;
while (cin >> ival1) {
    ivec1.push_back(ival1);
}
cin.clear();

cout << "enter numbers for vector 2 : " << endl;
while (cin >> ival2) {
    ivec2.push_back(ival2);
}