類和對(duì)象課件

1、參考：參考：C+C+程序設(shè)計(jì)教程程序設(shè)計(jì)教程 p106p110p106p110第六講第六講 類和對(duì)象（類和對(duì)象（5）C+C+對(duì)象數(shù)組對(duì)象及對(duì)象成員與指針q指向?qū)ο蟮闹羔榪this指針q對(duì)象的const指針對(duì)象引用及對(duì)象的常引用對(duì)象作為函數(shù)參數(shù)C+C+回憶我們?cè)?jīng)學(xué)過的數(shù)組int iarr3;struct student sarr3;int *p3;int (*p)3)5;void (*p5)( int x,int y );類型相同的變量的集合C+C+1 1、概念：、概念：如果數(shù)組元素都為類類型，我們把這樣的數(shù)組成為對(duì)象數(shù)組string arr9;C+C+2 2、聲明：、聲明：類名 數(shù)組名元素個(gè)

2、數(shù)；類名 數(shù)組名行數(shù)列數(shù);new 類名元素個(gè)數(shù);new 類名行數(shù)列數(shù);多維數(shù)組的格式與此類似C+C+3 3、初始化：、初始化：回憶內(nèi)置類型數(shù)組的初始化方式方式例例棧區(qū)棧區(qū)全局區(qū)全局區(qū)全部int a3 = 1,2,3 ;部分int a3 = 1,2 ;省略長度int a = 1,2,3 ;堆區(qū)堆區(qū)int *p = new int3;delete p;int *p = new int3();/delete p;DEMO 9_0DEMO 9_0C+C+對(duì)象數(shù)組的初始化方式方式例例棧區(qū)棧區(qū)全局區(qū)全局區(qū)全部Point arr2= Point(1,1),Point(2,2) ;部分Point arr2 =

3、 Point(1,1) ;省略長度Point arr = Point(1,1),Point(2,2);默認(rèn)Point arr3;堆區(qū)堆區(qū)point *p = new Point2;C+C+ 注意注意 堆對(duì)象數(shù)組不能顯示初始化Point *p = new Point3(Point(1,2),Point(2,2);一個(gè)數(shù)組元素就是一個(gè)對(duì)象,數(shù)組元素引用成員的方法與對(duì)象相同cout getX() : getY();cout (*p).getX() : (*p).getY(); cout arr0.getX() : 成員法三、法三、(對(duì)象數(shù)組名+下標(biāo))-成員 ( *(對(duì)象數(shù)組名+下標(biāo)) ).成員 對(duì)象

4、數(shù)組名下標(biāo).成員C+C+9_1. .class Pointpublic: Point( double aX = 0, double aY = 0 ); Point(); double GetX(); double GetY();private: double m_dX; double m_dY;double Point:GetX() return m_dX; double Point:GetY() return m_dY; Point:Point( double aX,double aY ) m_iX = aX; m_iY = aY; cout Executing Constructor. e

5、ndl;Point:Point() cout Executing Destructor. endl;int main() Point array3 = Point(3,4),Point(5,8) ; Point *p = array; for(; parray+3; p+) cout ( GetX() , (*p).GetY() ) getX(); /常指針只能引用常成員函數(shù)常指針只能引用常成員函數(shù) /指向常量的指針指向常量的指針Point * const KKp2 = &obj; Point * const KKp1 = &Kobj; /ErrorDEMO 9_12聲明：聲明

6、：與內(nèi)置類型的const指針規(guī)則同C+C+對(duì)象數(shù)組對(duì)象及對(duì)象成員與指針q指向?qū)ο蟮闹羔榪對(duì)象的const指針qthis指針對(duì)象引用及對(duì)象的常引用對(duì)象作為函數(shù)參數(shù)C+C+每個(gè)對(duì)象中的數(shù)據(jù)成員都分別占有存儲(chǔ)空間，如果對(duì)同一個(gè)類定義了N個(gè)對(duì)象，則有N組同樣大小的空間以存放N個(gè)對(duì)象中的數(shù)據(jù)成員，但是不同的對(duì)象都調(diào)用同一個(gè)函數(shù)代碼段。那么，當(dāng)不同對(duì)象的成員函數(shù)引用成員員時(shí)，怎么能保證引用的是指定對(duì)象的數(shù)據(jù)成員呢？為了確定究竟是哪個(gè)對(duì)象在引用當(dāng)前成員函數(shù)，C+引入了this指針問題的產(chǎn)生：問題的產(chǎn)生：C+C+什么是什么是this指針：指針：指向當(dāng)前對(duì)象的指針變量，每個(gè)成員函數(shù)都含有一個(gè)指向本類對(duì)象的thi

7、s指針。DEMO 9_2C+C+對(duì)象在內(nèi)存中分配空間的順序?yàn)椋合榷x的對(duì)象占高字節(jié)，后定義的對(duì)象占低字節(jié)C+C+注意：注意：引用成員函數(shù)時(shí)，在成員函數(shù)的參數(shù)表中會(huì)自動(dòng)添加一個(gè)該對(duì)象的指針a1.Print( &a1 );系統(tǒng)會(huì)為每個(gè)一成員函數(shù)自動(dòng)添加一個(gè)this指針void A:Print( A *this ) this指針不能顯示的定義，我們只能使用它，通常如果希望成員函數(shù)返回本類對(duì)象或者本對(duì)象地址時(shí)顯示的使用this指針this指針主要用于運(yùn)算符重載 DEMO stringC+C+如果成員函數(shù)返回本類對(duì)象的引用或指針則訪問成員的方式有些特殊class Atestpublic: Ate

8、st &print1( ) cout print1 endl; return *this; Atest *print2( ) cout print2 print1( ); system(PAUSE); return 0;9_3C+C+對(duì)象數(shù)組對(duì)象及對(duì)象成員與指針q指向?qū)ο蟮闹羔榪this指針對(duì)象引用及對(duì)象的常引用對(duì)象作為函數(shù)參數(shù)C+C+int ival = 3;int &rival = ival;const int &Kival = ival;const int kival = 3;int &rival = kival; /ERRORconst int &

9、;Kival = kival;const int &Kival = 3;1、回憶內(nèi)置類型的引用const引用可以指向字面值常量C+C+2、對(duì)象的引用:與內(nèi)置類型引用語法規(guī)則類似class Testpublic: Test(int arg = 0) m_iVal = arg; int get() return m_iVal private: int m_iVal;int main() Test obj; Test &ref = obj; /對(duì)象引用對(duì)象引用 const Test &kref = obj; cout kref.get();/Error const Test

10、kobj; Test &ref = kobj;/Error const Test &r = kobj; const Test *p = &kobj; return 0;常對(duì)象、常指針、常引用、只能引用常成員常對(duì)象只能被指向常量的指針或常引用指向C+C+. .Point p1(10,20),p2(30,40);Point &r = p1;void f() cout p1= ( p1.GetX() , p1.GetY() ); cout p2= ( p2.GetX() , p2.GetY() ); cout r= ( r.GetX() , r.GetY() ) en

11、dl;int main() cout original p1,p2,pr endl; f(); r = p2; cout after pr=p2, p1,p2,pr: endl; f(); r = Point(100,200); cout after pr=Point(100,200), p1,p2,pr: endl; f(); return 0;9_4C+C+C+C+對(duì)象數(shù)組對(duì)象及對(duì)象成員與指針對(duì)象引用及對(duì)象的常引用對(duì)象與函數(shù)參數(shù)q對(duì)象作函數(shù)參數(shù)q對(duì)象指針作函數(shù)參數(shù)q對(duì)象引用做函數(shù)參數(shù)C+C+void s ax, int ay) int temp=0; temp = ax; ax = ay;

12、 ay = temp;int main() int ival1 = 3,ival2 = 5; s); return 0;1、變量作為函數(shù)參數(shù)l形參開辟內(nèi)存單元，值傳遞35axayival1ival2C+C+void s arg1,Point arg2) Point temp=0; temp = arg1; arg1 = arg2; arg2 = temp;int main() Point obj1(1,1),obj2(2,2); s, obj2); return 0;2、對(duì)象作為函數(shù)參數(shù)形參開辟內(nèi)存單元，值傳遞調(diào)用拷貝構(gòu)造函數(shù)arg1obj1obj2arg2特點(diǎn)：值傳遞，開銷大C+C+DEMO

13、 9_8C+C+對(duì)象數(shù)組對(duì)象及對(duì)象成員與指針對(duì)象引用及對(duì)象的常引用對(duì)象與函數(shù)參數(shù)q對(duì)象作函數(shù)參數(shù)q對(duì)象指針作函數(shù)參數(shù)q對(duì)象引用做函數(shù)參數(shù)C+C+void s *p1, int*p2) int temp = 0; temp = *p1; *p1 = *p2; *p2 = temp;int main() int ival1 = 3,ival2 = 5; s, &ival2); return 0;1、回憶指針變量作為函數(shù)參數(shù)p1p2&ival1&ival2ival1ival2傳遞變量地址形參開辟內(nèi)存單元，值傳遞C+C+2、對(duì)象指針作為函數(shù)參數(shù)p1p2&obj1&

14、;obj2obj1obj2傳遞對(duì)象地址形參開辟內(nèi)存單元，值傳遞不會(huì)調(diào)用拷貝構(gòu)造函數(shù)void s *p1, Point *p2) Test temp; temp = *p1; *p1 = *p2; *p2 = temp;int main() Point obj1(3),obj2(5); s, &obj2); return 0;C+C+DEMO 9_9C+C+對(duì)象數(shù)組對(duì)象及對(duì)象成員與指針對(duì)象引用及對(duì)象的常引用對(duì)象與函數(shù)參數(shù)q對(duì)象作函數(shù)參數(shù)q對(duì)象指針作函數(shù)參數(shù)q對(duì)象引用做函數(shù)參數(shù)C+C+void s &r1, int &r2) int temp; temp = r1; r1 = r2; r2 = temp;int main() int ival1(3),ival2(5); s, ival2); return 0;35r1r2obj1obj21、回憶變量引用作為函數(shù)參數(shù)形參不開辟內(nèi)存，址傳遞C+C+2、對(duì)象引用作為函數(shù)參數(shù)形參不開辟內(nèi)存，址傳遞不會(huì)