int *p1[2];    // p1是一個(gè)數(shù)組，元素個(gè)數(shù)為2，每個(gè)元素為(int*)
int *(p2[2]);  // 等價(jià)于*p2[2]，p2是一個(gè)數(shù)組
int (*p3)[2];  // p3是一個(gè)指針，指向一個(gè)int數(shù)組，這個(gè)int數(shù)組的元素個(gè)數(shù)必須是2！

int *p1[2];    // 定義語句：先看[]:p1是一個(gè)數(shù)組，元素個(gè)數(shù)為2，每個(gè)元素為(int*)。等價(jià)于*(p1[2])
int (*p2)[2];  // 定義語句：先看*: p2是一個(gè)指針，指向一個(gè)int數(shù)組，這個(gè)int數(shù)組的元素個(gè)數(shù)必須是2！
cout << "*p1[0] = " << *p1[0] << endl;     // 執(zhí)行語句：先看[]：先取第0個(gè)元素，再解引用。等價(jià)于*(p1[0])
cout << "(*p2)[0] = " << (*p2)[0] << endl; // 執(zhí)行語句：先看*：先解引用，再取第0個(gè)元素

#include <iostream>
using namespace std;

int main(){	
	// []的優(yōu)先級(jí)高于*，因此下面的p1是數(shù)組，p2是指針：
	int *p1[2];    // p1是一個(gè)數(shù)組，元素個(gè)數(shù)為2，每個(gè)元素為(int*)。等價(jià)于*(p1[2])
	int (*p2)[2];  // p2是一個(gè)指針，指向一個(gè)int數(shù)組，這個(gè)int數(shù)組的元素個(gè)數(shù)必須是2！
	int a = 1, b = 2;
	int c[2] = {4,5};
	p1[0] = &a;
	p1[1] = &b;
	p2 = &c;
	cout << "*p1[0] = " << *p1[0] << endl;
	cout << "*p1[1] = " << *p1[1] << endl;
	cout << "*(p1[0]) = " << *(p1[0]) << endl;  // 與上面兩條等價(jià)
	cout << "*(p1[1]) = " << *(p1[1]) << endl;
	cout << "(*p2)[0] = " << (*p2)[0] << endl;  
	cout << "(*p2)[1] = " << (*p2)[1] << endl;
	
	return 0;
}

*p1[0] = 1
*p1[1] = 2
*(p1[0]) = 1
*(p1[1]) = 2
(*p2)[0] = 4
(*p2)[1] = 5

#include <iostream>
#include <string>
using namespace std;

class Student{
public:
	Student(string name, int id):_name(name),_id(id){}
	void printInfo(){
		cout << "I am a student. My name is " << _name << ". My id is " << _id << endl;
	}
	void operator()(){
		printInfo();
	}
protected:
	string _name;
	int _id;
};

class Student2 : public Student{
public:
	Student2(string name, int id):Student(name, id){}
	void printInfo(){
		cout << "I am a super Student!!! " << endl;
	}
	void operator()(){
		cout << "I am Student2!!!" << endl;
	}
};

struct StudentWrapper{
	Student* _ps;
	StudentWrapper(Student* ps):_ps(ps){}
	Student* operator()(){return _ps;}
};

int main(){	
	// .和(), ->和()平級(jí)：從左向右
	cout << "-----------------1------------------" << endl;
	Student s1("Bob",101), s2("Jack", 102);
	Student *ps1 = new Student("Eric",103);
	s1.printInfo();
	s2.printInfo();
	ps1->printInfo();

	// .高于*：先結(jié)合.
	cout << "-----------------2------------------" << endl;
	// 下面這條語句報(bào)錯(cuò)：先調(diào)用.printInfo()，再*，因此會(huì)報(bào)錯(cuò)
	// *ps1.printInfo();  // error: request for member 'printInfo' in 'ps1'
	(*ps1).printInfo(); 
			
	// .和()高于*：先結(jié)合()和.（從右向左），最后結(jié)合*
	cout << "-----------------3------------------" << endl;
	StudentWrapper sw(ps1);
	// 下面這條語句報(bào)錯(cuò)：先結(jié)合sw()，再結(jié)合.printInfo()，最后結(jié)合*，因此會(huì)報(bào)錯(cuò)
	// *sw().printInfo(); // error: request for member 'printInfo' in 'sw.StudentWrapper::operator()()'
	(*sw()).printInfo(); // correct：先sw()，再*sw()，再(*sw()).printInfo()
	// 下面這條語句報(bào)錯(cuò)：先結(jié)合sw()，再結(jié)合()，最后結(jié)合*，因此會(huì)報(bào)錯(cuò)
	// *sw()(); // error: expression cannot be used as a function
	(*sw())(); // correct：先sw()，再*sw()，再(*sw())()

	// (int)和()/[]：先結(jié)合()和[]，再強(qiáng)轉(zhuǎn)
	cout << "-----------------4------------------" << endl;
	Student2 ss("Alice", 999), sss("Jason", 998), ssArray[2] = {ss, sss};
	ss();   // 調(diào)用Student2::operator()
	// 下面這條語句報(bào)錯(cuò)，因?yàn)闀?huì)先結(jié)合ss()，再強(qiáng)制轉(zhuǎn)換
	// (Student)ss(); // error: invalid use of void expression
	((Student)ss)(); // correct: 調(diào)用Student::operator()
	// 下面這條語句報(bào)錯(cuò)，因?yàn)闀?huì)先結(jié)合ssArray[0], 再ssArray[0]()，再強(qiáng)制轉(zhuǎn)換
	// (Student)ssArray[0](); // error: invalid use of void expression
	((Student)ssArray[1])(); // correct：將ssArray[1]強(qiáng)制轉(zhuǎn)換為Student類型后，調(diào)用其()方法

	// ()高于.*和->*：先結(jié)合()
	cout << "-----------------5------------------" << endl;
	void (Student::*fp)();
	fp = Student::printInfo;
	// s1.*fp();   // error: must use '.*' or '->*' to call pointer-to-member function in 'fp (...)'
	(s1.*fp)();
	(s2.*fp)();
	// ps1->*fp(); // error: must use '.*' or '->*' to call pointer-to-member function in 'fp (...)'
	(ps1->*fp)(); 
	
	// (int)高于.*和->*：先結(jié)合(int)
	cout << "-----------------6------------------" << endl;
	Student2 *ssp = &sss;   // Jason
	void (Student2::*fp2)();
	fp2 = Student2::printInfo;
	(ss.*fp2)();
	((Student)ss.*fp)();  // 先將ss強(qiáng)轉(zhuǎn)為Student，然后調(diào)用Student::printInfo()，注意是.*fp而不是.*fp2
	((Student*)ssp->*fp)();  // 先將ssp強(qiáng)轉(zhuǎn)為Student*，然后調(diào)用Student::printInfo()，注意是.*fp而不是.*fp2

	// *高于.*和->*：先結(jié)合*
	cout << "-----------------7------------------" << endl;
	(*ssp.*fp2)();   // 先*ssp，再.*fp2
	Student2 **sspp = &ssp;
	(*sspp->*fp2)(); // 先*sspp，再->*fp2
	
	delete ps1;
	return 0;
}

-----------------1------------------
I am a student. My name is Bob. My id is 101
I am a student. My name is Jack. My id is 102
I am a student. My name is Eric. My id is 103
-----------------2------------------
I am a student. My name is Eric. My id is 103
-----------------3------------------
I am a student. My name is Eric. My id is 103
I am a student. My name is Eric. My id is 103
-----------------4------------------
I am Student2!!!
I am a student. My name is Alice. My id is 999
I am a student. My name is Jason. My id is 998
-----------------5------------------
I am a student. My name is Bob. My id is 101
I am a student. My name is Jack. My id is 102
I am a student. My name is Eric. My id is 103
-----------------6------------------
I am a super Student!!!
I am a student. My name is Alice. My id is 999
I am a student. My name is Jason. My id is 998
-----------------7------------------
I am a super Student!!!
I am a super Student!!!