やったこと
値が整数かどうかをみます。
確認環境
$ g++ --version
g++ (Homebrew GCC 9.2.0) 9.2.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
調査
test.cpp
#include <bits/stdc++.h>
using namespace std;
int main() {
double d1 = pow(3, 0.5);
double d2 = 2.0;
cout << (d1 == floor(d1)) << endl;
cout << (d2 == floor(d2)) << endl;
}
出力結果
0
1