实验9 类和对象（二）
实验 9.1
阅读程序啥的莫得难度，不过修改程序这个要求很玄奇
在main函数中调用fun函数，在fun函数中调用change和display函数。在fun函数中使用对象的引用（Student&）作为形参。
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
|
#include <iostream>
using namespace std;
class Student
{
public:
Student(int n, float s):num(n), score(s) {}
void change(int n, float s) {num = n; score = s;}
void display() {cout<< num << " " << score <<endl;}
private:
int num;
float score;
};
Student stud(101,78.5);
void fun(Student &)
{
stud.display();
stud.change(101,80.5);
stud.display();
}
int main()
{
fun(stud);
//int sundea;cin >> sundea;
return 0;
}
|
实验 9.2
大概就是给数据算数，模拟就完事了
不过要用静态数据成员和静态数据函数
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
|
#include <iostream>
using namespace std;
class Product
{
public:
Product(int m, int q, float p): num(m), quantity(q), price(p){};
void total();
static float average();
static void display();
private:
int num;
int quantity;
float price;
static float discount;
static float sum;
static int n;
};
//求钱和数量
void Product::total()
{
float rate = 1.0;
if (quantity > 10) rate *= 0.98;
sum += quantity*price*rate*(1-discount);
n += quantity;
}
//输出
void Product::display()
{
cout<< sum <<endl;
cout<< average() <<endl;
}
//求均
float Product::average()
{ return (sum/n);}
//成员初始化
float Product::discount = 0.05;
float Product::sum = 0;
int Product::n = 0;
int main()
{
Product Prod[3] = {Product(101,5,23.5),Product(102,12,24.56),Product(103,100,21.5)};
for(int i = 0; i < 3; i++)
Prod[i].total();
Product::display();
//int sundea;cin>>sundea;
return 0;
}
|
(PS:这个程序好像会有几个warning，不过只要不是error，我们就不必在意)
实验 8.3
分析运行程序然后注意友元函数Time::display的作用，然后把他放在类外，再在Time,Date类中将其声明为友元函数。在主函数中再调用display函数，并分别引用Time和Date两个类的对象的私有数据。
大概就是考察如何使用友元函数，即如何在类外调用类内的private数据，这个在我的另一篇文章里有些哦！
这道题的最终代码如下，实际上改动不是很大：
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
|
#include <iostream>
using namespace std;
class Date;
class Time {
public:
Time(int, int, int);
friend void display(Time &, Date &);
private:
int hour, minute, sec;
};
class Date {
public:
Date(int, int, int);
friend void display(Time &, Date &);
private:
int month, day, year;
};
Time::Time(int h, int m, int s) {
hour = h;
minute = m;
sec = s;
}
void display(Time &t, Date &d) {
cout << d.month <<"/"<< d.day << "/" << d.year <<endl;
cout << t.hour <<":"<< t.minute <<":"<< t.sec <<endl;
}
Date::Date(int m, int d, int y) {
month = m;
day = d;
year = y;
}
int main()
{
Time t1(10, 13, 56);
Date d1(12, 25, 2004);
display(t1,d1);
// int sundea;cin>>sundea;
return 0;
}
|
实验 8.4
将函数由类内定义改为类外虽然简单但是繁琐
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
|
#include <iostream>
using namespace std;
template<class numtype> //定义类模板
class Compare {
public:
Compare(numtype a, numtype b)
{
x = a; y = b;
}
numtype max();
numtype min();
private:
numtype x, y;
};
template <class numtype>
numtype Compare <numtype>::max()
{
return (x > y) ? x : y;
};
template <class numtype>
numtype Compare <numtype>::min()
{
return (x < y) ? x : y;
};
int main()
{
Compare<int> cmp1(3, 7); //比较整数
cout << cmp1.max() << " is the Maximum of two interger numbers." << endl;
cout << cmp1.min() << " is the Minimum of two interger numbers." << endl << endl;
Compare<float> cmp2(45.78, 93.6); //比较浮点数
cout << cmp2.max() << " is the Maximum of two interger numbers." << endl;
cout << cmp2.min() << " is the Minimum of two interger numbers." << endl << endl;
Compare<char> cmp3('a', 'A'); //比较字符
cout << cmp3.max() << " is the Maximum of two interger numbers." << endl;
cout << cmp3.min() << " is the Minimum of two interger numbers." << endl << endl;
int sundea; cin >> sundea;
return 0;
}
|
（PS：这里我出了一个很想当然的错误，具体可以移步这里来查看