下面C++代码执行后的输出是 ( ) 。

#include

using namespace std;

int main() {

int a[9] = {3, 1, 4, 0, 5, 9, 2, 6, 5};

int missing = 0;

while (true) {

bool found = false;

for (int i = 0; i < 9; i++) {

if (a[i] == missing) {

found = true;

break;

}

}

if (!found) break;

missing++;

}

cout << "Missing number is: " << missing;

return 0;

}