学步园

//============================================================================
// Name        : CppLab.cpp
// Author      : sodino
// Version     :
// Copyright   : Your copyright notice
// Description : Hello World in C++, Ansi-style
//============================================================================

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

struct Student{
	string name;
};

int main() {
	void print(Student);
	void print_point(Student *);
	void print_reference(Student &);
	struct Student stu = {"Yao ming"};
	cout << "main &stu=" << &stu << endl << endl;

	print(stu);
	cout << "after print() name=" << stu.name << " no changed."<< endl << endl;

	print_point(&stu);
	cout << "after print_point() name=" << stu.name << " has been modified." << endl << endl;

	print_reference(stu);
	cout << "after print_reference() name=" << stu.name << " has been modified." << endl;
	return 0;
}

void print(Student stu) {
	// 实参转形参，会消耗额外的时间。print_reference()则效率高许多。
	cout << "print() stu address=" << &stu << " is different."<< endl; // 形参stu与函数体外的stu是两个不同的对象！！
	stu.name = "new.name"; // 这里的赋值并不会改变函数体外stu的name
	cout << "print() set new name=" << stu.name << endl;
}

void print_point(Student * stu) {
	stu->name = "new.point.name";
	cout << "print_point() set new name=" << stu->name << endl;
}

void print_reference(Student &stu) {
	stu.name = "new.reference.name";
	cout << "set new name=" << stu.name << endl;
}

main &stu=0x7fff5eabfbc8

print() stu address=0x7fff5eabfba0 is different.
print() set new name=new.name
after print() name=Yao ming no changed.

print_point() set new name=new.point.name
after print_point() name=new.point.name has been modified.

set new name=new.reference.name
after print_reference() name=new.reference.name has been modified.