構(gòu)造函數(shù)

#include<iostream> using namespace std;class Person { public:int age;Person() {cout << "無參構(gòu)造" << endl;}Person(int a) {age = a;cout << "有參構(gòu)造" << endl;}//拷貝構(gòu)造參數(shù)Person(const Person &p) {age = p.age;cout << "拷貝構(gòu)造" << endl;}~Person() {cout << "析構(gòu)函數(shù)" << endl;}}; int main1() { // Person p1;//無參構(gòu)造 // Person p2(10);//有參構(gòu)造 // Person p3(p2);//拷貝構(gòu)造//cout << "p2的age=" << p2.age << endl;//cout << "p3的age=" << p3.age << endl;//調(diào)用默認(rèn)構(gòu)造函數(shù)時(shí)不加()//2.顯示法Person p1;Person p2 = Person(15);Person p3 = Person(p2);//注意事項(xiàng)，不要利用拷貝構(gòu)造函數(shù)來初始化一個(gè)匿名對(duì)象, 編譯器會(huì)認(rèn)為是對(duì)象的聲明//Person(p3);//3.隱式轉(zhuǎn)換法//Person p4 = 10; ////Person p5 = p4;return 0; }

深拷貝與淺拷貝

#include<iostream> using namespace std; class Person { public:int m_age;int* m_height;Person() {cout << "無參構(gòu)造" << endl;}Person(int age, int height) {m_age = age;m_height = new int(height);cout << "有參構(gòu)造" << endl;}//省略此步即為淺拷貝，編譯器默認(rèn)的拷貝構(gòu)造函數(shù)為淺拷貝，析構(gòu)時(shí)會(huì)重復(fù)釋放指針導(dǎo)致報(bào)錯(cuò)//Person(const Person &p) {// m_age = p.m_age;// m_height = new int(*p.m_height);// cout << "拷貝構(gòu)造" << endl;//}~Person() {if (m_height != NULL) {delete(m_height);m_height = NULL;}cout << "析構(gòu)函數(shù)" << endl;}}; void testG() {Person p1(15, 177);Person p2(p1);cout << "p1的age = " << p1.m_age << " p1的height = " << *p1.m_height<< endl;cout << "p2的age = " << p2.m_age << " p2的height = " << *p2.m_height<< endl;} int main() {testG();return 0;}

對(duì)象特性——初始化列表

#include<iostream> using namespace std; class Person { public:int m_a;int m_b;int m_c;Person(int a, int b, int c) :m_a(a), m_b(b), m_c(c) {}}; void test() {Person p(15, 25, 0);cout << p.m_a << endl;cout << p.m_b << endl;cout << p.m_c << endl;}int main() {test();}

類對(duì)象作成員

#include<iostream> using namespace std; class Phone { public:string m_phoneName;Phone(string phoneName) {m_phoneName = phoneName;cout << "構(gòu)造phone" << endl;}~Phone() {cout << "析構(gòu)phone" << endl;} };class Person { public:Phone m_p;string m_name;Person(string phoneName, string name) :m_p(phoneName), m_name(name){cout << "構(gòu)造person" << endl;}~Person() {cout << "析構(gòu)person" << endl;} };void test() {Person p("iPhone", "motherfucker");cout << p.m_p.m_phoneName << endl;cout << p.m_name << endl;};int main() {test();return 0; } //打印結(jié)果，注意先構(gòu)造對(duì)象成員，析構(gòu)時(shí)順序相反//構(gòu)造phone //構(gòu)造person //iPhone //motherfucker //析構(gòu)person //析構(gòu)phone

靜態(tài)成員——靜態(tài)函數(shù)

#include<iostream> using namespace std; class Person { public:int m_b;static void func() {cout << "調(diào)用靜態(tài)函數(shù)" << endl;s_a = 100;//m_b = 0;靜態(tài)成員函數(shù)只能訪問靜態(tài)變量，不能訪問成員變量} private:static int s_a;}; int Person::s_a = 0; void test() {Person p;p.func();Person::func; }int main() {test();return 0; }

成員變量與成員函數(shù)分開存儲(chǔ)

#include<iostream> using namespace std; //成員變量和成員函數(shù)分開存儲(chǔ) class Person {int m_A;//非靜態(tài)成員變量 屬于類的對(duì)象上static int m_b;//靜態(tài)的成員變量與成員函數(shù) 不屬于類的對(duì)象上void func(){}//非靜態(tài) 不屬于類的對(duì)象上}; void test01() {Person p;//空對(duì)象占用空間1個(gè)字節(jié)//c++編譯器給空對(duì)象分配一個(gè)字節(jié)空間，是為了區(qū)分空對(duì)象占用的位置//每個(gè)空對(duì)象都有一個(gè)獨(dú)一無二的內(nèi)存地址cout << "size of p = " << sizeof(p) << endl; } int main() {test01(); }

總結(jié)

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