16.使用this指针复制数据.
头文件:
1 #include <iostream>
2
3 using namespace std;
4
5 class Obj
6 {
7 int a, b;
8
9 public:
10 Obj(int x = 0, int y = 0)
11 {
12 a = x;
13 b = y;
14 }
15
16 void copy(Obj &);
17 void display()
18 {
19 cout << "a = " << a << ", b = " << b << endl;
20 }
21 };
22
23 void Obj::copy(Obj &aObj)
24 {
25 if (this == &aObj)
26 return;
27 this->a = aObj.a;
28 this->b = aObj.b;
29 }
obj.h
源文件:
1 #include "obj.h"
2
3 void main(void)
4 {
5 Obj x1(22, 25), x2(33, 46);
6
7 cout << "x1: ";
8 x1.display();
9 cout << "x2: ";
10 x2.display();
11 x1.copy(x2);
12 cout << "x1: ";
13 x1.display();
14 }
结果:
x1: a = 22, b = 25
x2: a = 33, b = 46
x1: a = 33, b = 46
Mark:
当一个对象调用成员函数时,系统先将该对象的地址赋给this指针,然后调用成员函数,成员函数对成员数据进行操作时,隐含使用了this指针.
17.完整实现str类的例子.
头文件:
1 #ifndef _STR_H
2 #define _STR_H
3
4 #include <iostream>
5 #include <cstring>
6
7 using namespace std;
8
9 class str
10 {
11 private:
12 char *st;
13
14 public:
15 str(char *s);
16 str(str &s);
17 str & operator = (str &a);
18 str & operator = (char *s);
19 void print()
20 {
21 cout << st << endl;
22 }
23
24 ~str()
25 {
26 delete st;
27 }
28 };
29
30 str::str(char *s)
31 {
32 st = new char[strlen(s) + 1];
33 strcpy(st, s);
34 }
35
36 str::str(str &a)
37 {
38 st = new char[strlen(a.st) + 1];
39 strcpy(st, a.st);
40 }
41
42 str & str::operator = (str &a)
43 {
44 if (this == &a)
45 return *this;
46 delete st;
47 st = new char[strlen(a.st) + 1];
48 strcpy(st, a.st);
49 return *this;
50 }
51
52 str & str::operator = (char *s)
53 {
54 delete st;
55 st = new char[strlen(s) + 1];
56 strcpy(st, s);
57 return *this;
58 }
59
60 #endif
str.h
源文件:
1 #include "str.h"
2
3 void main(void)
4 {
5 str s1("We"), s2("They"), s3(s1);
6
7 s1.print();
8 s2.print();
9 s3.print();
10
11 s2 = s1 = s3;
12 s3 = "Go home!";
13 s3 = s3;
14 s1.print();
15 s2.print();
16 s3.print();
17 }
结果:
We
They
We
We
We
Go home!
18.求4个数的最大值的类模板程序.
头文件:
1 #ifndef _MAX4_H
2 #define _MAX4_H
3
4 #include <iostream>
5
6 using namespace std;
7
8 template <class T>
9 class Max4
10 {
11 T a, b, c, d;
12 T Max(T a, T b)
13 {
14 return (a > b) ? a : b;
15 }
16
17 public:
18 Max4(T, T, T, T);
19 T Max(void);
20 };
21
22 template <class T>
23 Max4<T>::Max4(T x1, T x2, T x3, T x4):a(x1),b(x2),c(x3),d(x4)
24 {
25 }
26
27 template <class T>
28 T Max4<T>::Max(void)
29 {
30 return Max(Max(a, b), Max(c, d));
31 }
32
33 #endif
max4.h
源文件:
1 #include "max4.h"
2
3 void main(void)
4 {
5 Max4<char> C(‘W‘, ‘w‘, ‘a‘, ‘A‘);
6 Max4<int> A(-25, -67, -66, -256);
7 Max4<double> B(1.25, 4.3, -8.6, 3.5);
8 cout << C.Max() << " " << A.Max() << " " << B.Max() << endl;
9 }
结果:
w -25 4.3
19.演示对4个数字求和的类模板程序.
头文件:
1 #ifndef _SUM_H
2 #define _SUM_H
3
4 template <class T, int size = 4>
5 class Sum
6 {
7 private:
8 T m[size];
9
10 public:
11 Sum(T a, T b, T c, T d)
12 {
13 m[0] = a;
14 m[1] = b;
15 m[2] = c;
16 m[3] = d;
17 }
18
19 T S()
20 {
21 return m[0] + m[1] + m[2] + m[3];
22 }
23 };
24
25 #endif
sum.h
源文件:
1 #include <iostream>
2 #include "sum.h"
3
4 using namespace std;
5
6 void main(void)
7 {
8 Sum<int, 4> num1(-23, 5, 8, -2);
9 Sum<float, 4> f1(3.5f, -8.5f, 8.8f, 9.7f);
10 Sum<double, 4> d1(355.4, 253.8, 456.7, -67.8);
11 Sum<char, 4> c1(‘W‘, -2, -1, -1); //字符减,等效于‘W‘,‘U‘,‘T‘,‘S‘
12 cout << num1.S() << ", " << f1.S() << ", " << d1.S() << ", " << c1.S() << endl;
13 }
结果:
-12, 13.5, 998.1, S
20.使用缺省内联函数实现单一继承
头文件:
1 #include <iostream>
2
3 using namespace std;
4
5 class Point
6 {
7 private:
8 int X, Y;
9
10 public:
11 Point(int a, int b)
12 {
13 X = a;
14 Y = b;
15 cout << "Point..." << endl;
16 }
17
18 void Showxy()
19 {
20 cout << "X = " << X << ", Y = " << Y << endl;
21 }
22
23 ~Point()
24 {
25 cout << "Delete Point" << endl;
26 }
27 };
28
29 class Rectangle:public Point
30 {
31 private:
32 int H, W;
33
34 public:
35 Rectangle(int a, int b, int h, int w):Point(a, b)
36 {
37 H = h;
38 W = w;
39 cout << "Rectangle..." << endl;
40 }
41
42 void Show()
43 {
44 cout << "H = " << H << ", W = " << W << endl;
45 }
46
47 ~Rectangle()
48 {
49 cout << "Delete Rectangle" << endl;
50 }
51 };
rectangle.h
源文件:
1 #include "rectangle.h"
2
3 void main(void)
4 {
5 Rectangle r1(3, 4, 5, 6);
6 r1.Showxy();
7 r1.Show();
8 }
结果:
Point...
Rectangle...
X = 3, Y = 4
H = 5, W = 6
Delete Rectangle
Delete Point
Mark:
当定义派生类的一个对象时,首先调用基类的构造函数,对基类成员进行初始化,然后执行派生类的构造函数,如果某个基类仍是一个派生类,则这个过程递归进行.
时间： 2024-12-13 18:20:23