while(i!=i){}

问给i赋什么值会进入死循环

当i是浮点类型，值为NAN时
＃i nclude <cmath>
＃i nclude <iostream>
using namespace std;

int main() {
  float i = -1;
  i = sqrt(i);
  cout << i << endl
       << (i==i) << endl
       << (i!=i) << endl
       << (i<0) << endl
       << (i>=0) << endl;
}

----------------------
nan
0
1
0
0