C++程序设计主要内容对象的初始化━━使用初始化数据列表对象的初始化━━使用构造函数构造函数构造函数━━在函数体中对各成员数据赋初值【例】（时钟类、构造函数重载）#include<iostream.h>classClock{inthour,minute,second;public:Clock(){hour=0;minute=0;second=0;cout<<“调用不带参的构造函数!\n”;}Clock(inth,intm,ints){hour=h;minute=m;second=s;cout<<“调用带3个参的构造函数!\n”;}voidsettime(inth,intm,ints){hour=h;minute=m;second=s;}voidshowtime(){cout<<hour<<“:”<<minute<<“:”<<second<<endl;}};voidmain(){Clockc1,c2(10,20,30);c1.showtime();c2.showtime();c2.settime(8,50,20);c2.showtime();}【例】（矩形类、带默认形参值的构造函数）#include<iostream.h>#include<math.h>classRectangle{floatleft,top,right,bottom;public:Rectangle(floatL=0,floatT=0,floatR=0,floatB=0){left=L;top=T;right=R;bottom=B;}voidset(floatL,floatT,floatR,floatB){left=L;top=T;right=R;bottom=B;}voidprint(){cout<<“left=”<<left<<“\ttop=”<<top<<‘\t’;cout<<“right=”<<right<<“\tbottom=”<<bottom<<‘\t’;cout<<“面积=”<<fabs(right-left)*fabs(bottom-top)<<endl;}};voidmain(){Rectangler0;r0.print();Rectangler1(10);r1.print();Rectangler2(10,20);r2.print();Rectangler3(10,20,30);r3.print();Rectangler4(10,20,30,40);r4.print();r0.set(1,2,3,4);r0.print();}默认的构造函数默认的构造函数默认的构造函数this指针━━成员函数中指向当前对象的指针this指针━━成员函数中指向当前对象的指针【例】（学生类、this指针）#include<iostream.h>#include<string.h>classStudent{intid;charname[8];intscore;public:Student(inti,char*na,ints){id=i;strcpy(name,na);score=s;cout<<“对象地址=”<<this<<“\t调用构造函数了!\n”;}voidprint(){cout<<“学号:”<<id<<“\t姓名:”<<name<<“\t成绩:”<<score<<endl;}};voidmain(){Students1(111,“张军”,99);Students2(222,“王红”,88);s1.print();s2.print();}对象的生存期和作用域【例】（矩形类、构造函数重载、全局对象、static局部对象、auto局部对象）#include<iostream.h>classRectangle{floatleft,top,right,bottom;public:Rectangle(floatL,floatT,floatR,floatB){left=L;top=T;right=R;bottom=B;cout<<“调用带4个参的构造函数!\n”;}Rectangle(floatL,floatT,floatR){left=L;top=T;right=R;bottom=0;cout<<“调用带3个参的构造函数!\n”;}Rectangle(floatL,floatT){left=L;top=T;right=0;bottom=0;cout<<“调用带2个参的构造函数!\n”;}Rectangle(floatL){left=L;top=0;right=0;bottom=0;cout<<“调用带1个参的构造函数!\n”;}