为什么我在编译时 ， Student st1可以完成初始化 而Student st1（）却不能初始化呢？

#include<iostream>

#include<string>

#include<cstdlib>

using namespace std;

class Teacher {

public:

Teacher() {

m_strName = "jame";

m_iAge = 16;

cout << "已经成功了！" << endl;

}

Teacher(string name, int age) {

m_strName = name;

m_iAge = age;

cout << "哈哈 你错了吧！" << endl;

}

string getName() {

return m_strName;

};

int getAge() {

return m_iAge;

};

private:

string m_strName;

int m_iAge;

 };

int main(void) {

Teacher st1;

//Teacher st2();\Teacher("jame",16);

Teacher *p=NULL;

p = new Teacher();

cout << p->getName() << " " << p->getAge() << endl;

delete p;

p = NULL;

system("pause");

return 0;

}