c++ - 关于std：cin的一个细节问题

Question

书上看到这个示例：

#include <iostream>
#include <string>
using namespace std;
int main()
{
    string buf;
    while (cin >> buf && !buf.empty())
        cout << 1;
}

我想问!buf.empty()有必要吗？，据我的理解，cin>>buf不接受空白字符，那就肯定不是空字符串了，所以while（cin>>buf）就行了.

Answer 1

][1]

In fact, there is no need to add spaces. By default, spaces and line breaks are not accepted