vector装入自定义类多个对象的时候复制构造函数参数必须有const修饰

#include<iostream>
#include<vector>
using namespace std;
class A{
private:
int value;
public:
A(){
cout << " constructor " << endl;

}
A(int n){
value=n;
cout << "constructor " << endl;
}

A(const A &other){//必须是const的，否则下面vector要报错
value = other.value;
cout << "copy " << endl;
}
/*	A(A o){
value = o.value;
}
*/	void print(){
cout << value << endl;
}
};

void print(A a){
a.print();
}

int main(){
/*A a(10);
A b = a;
A c(b);
b.print();
print(b);
*/
vector<A> v(10);

return 0;
}

$ ./a
constructor
copy
copy
copy
copy
copy
copy
copy
copy
copy
copy