为什么不能初始化？

#include <iostream>
#include <iomanip>
#include<string>
using namespace std;
struct student {
    int num;
    string name;
    char sex;
    int age ;
};
int main(){
    student stu={111,"liu",'F',12};
    cout<<stu.num<<endl;
    cout<<stu.name<<endl;
    cout<<stu.sex<<endl;
    cout<<stu.age<<endl;
    return 0;
}