扬州大学物理学院c++编程.docVIP

带缺省参数的函数+函数重载 #include iostream.h void ff(int a,int b,float c=4.5) {couta=a,b=b,c=cendl; } void main() {ff(1,2); ff(1,2,1.5); } 结果：a=1,b=2,c=4.5 a=1,b=2,c=1.5 This指针的使用 #include iostream using namespace std; class Tdate { public: void set(int m,int d,int y=2012) {this-month=m; this-day=d; this-year=y; } void print(){coutmonth/day/yearendl;} private: int month; int day; int year; }; void main() {Tdate a; a.set(8,14,2011); a.print (); } 有参无参构造函数 #include iostream.h class test {private: int num; float f; public: test(); test(int n, double f); } ; test::test() {num=0; f=1.2; coutDefaultendl; } test::test(int n, double f) { num=0; f=1.2; coutn=n,f=fendl; } void main() { test x; test y(10, 21.5); } 结果：Default n=10,f=21.5 拷贝构造函数 #include iostream.h class cat {private: int age; public: cat(); cat(cat ); }; cat::cat(){coutconstruction of aendl;} cat::cat(cat other) {age=other.age; coutconstruction from aendl;} void main() {cat a; cat b(a); } 友元函数 #include iostream.h class my { int x; int y; public: my(int ,int ); friend int sum(my a); friend void print(my a); }; my::my(int x1,int y1) {x=x1;y=y1;} int sum(my a) {return a.x+a.y;} void print(my a) { coutx=a.x y=a.yendl;} void main() {my a(10,12); coutthe sum is:sum(a)endl; print(a); } 继承与派生 #includeiostream.h class A { int m; public: A(int a,int b) {m=a+b;} int R() {return m;} }; class B:public A { int n; public: B(int a,int b,int m=0):A(a,b) {n=m;} int R() {return A::R();} int R2() {return n;} }; void main() {B ss(10,15,12); coutss.R2(),ss.R()endl; } 运算符重载 #includeiostream.h class P {public: P(int a,int b){x=a;y=b;}; P operator+(P); void OUT(){coutx=x,y=yendl;} protected: int x,y; }; P P::operator+(P a) {int n=x-a.x; int m=y-a.y; P l(n,m); return l;} void main() {P a(5,25); P b(2,30); P c(0,0); c=a+b; c.OUT(); }