无法使用cin读取字符串

For this simple piece of code:

对于这段简单的代码:

#include<iostream>
#include<string>
using std::cin;
using std::cout;
using std::string;

bool are_uniq_chars(string const&);

int main(){
string s;
cout << "Enter string: ";
cin >> s;
auto flag = are_uniq_chars(s);
#