某农业大学第七次实验（多态性）
| 1. | 函数模版及函数重载 【问题描述】 编写一个函数模版，能够处理整数、实数、串类对象的大小比较，返回两个值中的最小者。为了能够处理字符数组存储的字符串的大小比较，则需要使用函数重载的形式。为了能够处理串类对象的大小比较，则需要对串类实现关系运算符'>'或'<'的重载。 主函数如下，请勿修改： int main() { int x,y; double a,b; char c1[20],c2[20],c3[20],c4[20]; cin>>x>>y; cout< cin>>a>>b; cout< cin>>c1>>c2; cout< cin>>c3>>c4; String s1(c3),s2(c4); cout< return 0; } 5 9 13.2 7.8 Zhang Helen Wang Jack 5 7.8 Helen Jack |
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#include
using namespace std;
class String
{
private:
char *s;
public:
String()
{
}
String(const char *a)
{
s=new char[strlen(a)];
strcpy(s,a);
}
friend bool operator<(const String &s1, const String &s2)
{
if(strcmp(s1.s, s2.s)<0) return true;
else return false;
}
friend ostream& operator<<(ostream & out, String a)
{
out << a.s << endl;
return out;
}
};
double Min(double a,double b)
{
if(a
T Min(T a, T b)
{
return a>x>>y;
cout<>a>>b;
cout<>c1>>c2;
cout<>c3>>c4;
String s1(c3),s2(c4);
cout< | 2. | 学生类模板 【问题描述】 定义一个模板类Student，为了增强类的适用性，将学号设计为参数化类型，它可以实例化成字符串、长整形等；将成绩设计为参数化类型，它可以实例化成整形、浮点型、字符型（用来表示等级分）等。 template class Student{ private: TNo StudentID; //参数化类型，存储姓名 TScore score[num]; //参数化类型数组，存储num门课程的分数 public: void Input();//数据的录入 TScore MaxScore(); //查找score的最大值并返回该值 void Update(TScore sscore,int i);//更新学生的第i门课程成绩为sscore void SelectSort(); //采用选择排序法对学生成绩进行升序排列 void Print(); //输出所有学生的信息 }; 请注意String是自定义的class类型，参考如下： class String{ public: char Str[20]; friend istream &operator>>(istream &in, String &s); friend ostream &operator<<(ostream &out, String &s); }; 请自行设计主函数，并做如下声明。从键盘依次录入数据，然后分别调用四个成员函数执行得到所需的结果。 Student
zhao 82.5 96.3 73.5 2 74.5 【样例输出1】 96.3 zhao 74.5 82.5 96.3 【样例输入2】 ma 10 20 30 1 50 【样例输出2】 50 ma 10 30 50 【样例输入3】 zhang 82.3 50.5 92.1 1 62.3 【样例输出3】 92.1 zhang 62.3 82.3 92.1 【样例说明】 【评分标准】 |
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#include
using namespace std;
class String {
public:
char Str[20];
friend istream& operator>>(istream& in, String& s) {
in >> s.Str;
return in;
}
friend ostream& operator<<(ostream& out, const String& s) {
out << s.Str;
return out;
}
};
template
class Student {
private:
TNo StudentID;
TScore score[num];
public:
void Input() {
cin >> StudentID;
for (int i = 0; i < num; i++) {
cin >> score[i];
}
}
TScore MaxScore() {
TScore max = score[0];
for (int i = 1; i < num; i++) {
if (score[i] > max) {
max = score[i];
}
}
return max;
}
void Update(TScore sscore, int i) {
if (i >= 0 && i < num) {
score[i] = sscore;
}
}
void SelectSort() {
for (int i = 0; i < num - 1; i++) {
int minIndex = i;
for (int j = i + 1; j < num; j++) {
if (score[j] < score[minIndex]) {
minIndex = j;
}
}
if (minIndex != i) {
TScore temp = score[i];
score[i] = score[minIndex];
score[minIndex] = temp;
}
}
}
void Print() {
cout << StudentID;
for (int i = 0; i < num; i++) {
cout << " " << score[i];
}
cout << endl;
}
};
int main() {
Student student;
student.Input();
float newScore;
int courseIndex;
cin >> courseIndex >> newScore;
student.Update(newScore, courseIndex);
cout << student.MaxScore() << endl;
student.SelectSort();
student.Print();
return 0;
}
| 3. | 二进制类（运算符号的重载） 【问题描述】将一个16位二进制数表示成0和1的字符序列，即用一个字符数组来存放这个二进制数。在这个类中设置两个构造函数，一个是传递整数参数的，另一个是传递字符串参数的。因为用户在创建对象时传递的二进制数，可能是以整数形式给出，也可能是以数字串形式给出，系统应该都能接受。另外有一个类型转换函数int()，用来将类类型向整型转换，即将二进制形式的类对象转换为整形数。两个重载运算符“+”，“-”，用来完成两个二进制数之间的加减运算。 class binary { //定义二进制类 char bits[16]; //二进制字模数组 public: binary(char *); //字符串参数构造函数 binary(int); //整型参数构造函数 friend binary operator +(binary,binary); //重载“+”，友元函数 friend binary operator -(binary,binary); //重载“-”，友元函数 operator int(); //类类型转换函数，成员函数 friend ostream & operator <<(ostream &out, binary &b);//重载“<<”，以二进制形式输出 void print();//以整型形式输出 }; 主函数设计如下，请勿修改： int main(){ binary n1="1011"; binary n2=int(n1)+15; binary n3=n1-binary(7); cout< cout< cout< cout< n2=n2-binary(5); n2.print(); n3=n3+binary(5); n3.print(); cout< return 0; } 【样例输出】 0000000000001011 0000000000011010 0000000000000100 31 21 9 4 |
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#include
#include
#include
using namespace std;
class binary {
char bits[16];
public:
binary(char *s);
binary(int n);
friend binary operator+(binary b1, binary b2);
friend binary operator-(binary b1, binary b2);
operator int();
friend ostream & operator<<(ostream &out, binary &b);
void print();
};
binary::binary(char *s)
{
int i, size = strlen(s);
for (i = 0; i < 16 - size; i++)
{
bits[i] = '0';
}
for (int j = 0; j < size; j++,i++)
{
bits[i] = s[j];
}
}
binary::binary(int n)
{
int re, i = 0;
while (n != 0)
{
re = n % 2;
bits[i++] = re + 48;
n /= 2;
}
while (i<16)
{
bits[i++] = '0';
}
for (int k = 0, j = 15; k < j; k++, j--)
{
re = bits[k];
bits[k] = bits[j];
bits[j] = re;
}
}
binary::operator int()
{
int j = 0, ans = 0;
for (int i = 15; i >= 0; i--,j++)
{
ans += (bits[i] - 48)*pow(2, j);
}
return ans;
}
void binary::print()
{
cout << int(*this) << endl;
}
binary operator+(binary b1, binary b2)
{
binary temp(int(b1)+int(b2));
return temp;
}
binary operator-(binary b1, binary b2)
{
binary temp(int(b1)-int(b2));
return temp;
}
ostream & operator<<(ostream & out, binary & b)
{
for (int i = 0; i < 16; i++)
out << b.bits[i];
return out;
}
int main()
{
binary n1 = const_cast("1011");
binary n2 = int(n1) + 15;
binary n3 = n1 - binary(7);
cout << n1 << endl;
cout << n2 << endl;
cout << n3 << endl;
cout << int(n2) + 5 << endl;
n2 = n2 - binary(5);
n2.print();
n3 = n3 + binary(5);
n3.print();
cout << int(n3) - 5 << endl;
return 0;
}
| 4. | 时间类的改进（运算符重载） 【问题描述】对前面实验写过的Time类进行修改，删去Add和Sub成员函数，通过重载“+”、“-”运算符直接进行时间的加减运算。 提示： (1)可以用友元函数来实现“+”“-”运算符的重载。 (2)加法运算符可以是两个Time对象进行相加，也可以是一个表示秒数的int型数据加上一个Time对象，还可以是Time对象加上int型数据，得到的结果都是Time类型的对象。 (3)减法运算符可以是两个Time对象进行相减，也可以是Time对象减去一个表示秒数的int型数据，得到的结果都是Time类型的对象。 主函数设计如下，请勿修改： int main(){ Time t1(2,34),t2,t3; t2.SetTime(13,23,34); cout<<"t1+t2:"; t3=t1+t2;//两个Time类对象相加 t3.print_24(); cout<<"\nt1+65:"; t3=t1+65;//Time类对象加上65秒 t3.print_24(); cout<<"\n65+t1:"; t3=65+t1;//65秒加上Time类对象 t3.print_24(); cout<<"\nt2-t1:"; t3=t2-t1;//两个Time类对象相减 t3.print_24(); cout<<"\nt1-70:"; t3=t1-70;//Time类对象减去70秒 t3.print_24(); return 0; } 【样例输出】 t1+t2:15:57:34 t1+65:02:35:05 65+t1:02:35:05 t2-t1:10:49:34 t1-70:02:32:50 |
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#include
using namespace std;
class Time
{
int hour, minute, second;
public:
int SecCalc() { return(hour * 60 + minute) * 60 + second; }
Time(int h, int m, int s = 0);
Time(int s = 0);
void SetTime(int h = 0, int m = 0, int s = 0);
void print_12();
void print_24();
Time operator+(Time &t);
Time operator-(Time &t);
Time operator+(int s);
Time operator-(int s);
friend Time operator+(int s,Time &t);
friend Time operator-(int s, Time &t);
};
Time::Time(int h, int m, int s)
{
hour = h;
minute = m;
second = s;
}
Time::Time(int s)
{
hour = minute = second = 0;
for (int i = 0; i < s; i++)
{
second++;
if (second == 60)
{
second = 0;
minute++;
if (minute == 60)
{
hour++;
minute = 0;
}
}
}
}
void Time::SetTime(int h, int m, int s)
{
hour = h;
minute = m;
second = s;
}
void Time::print_12()
{
bool afternoon = false;
if (hour > 12)
{
if (hour - 12 < 10)
cout << "0";
cout << hour - 12 << ":";
afternoon = true;
}
else
{
if (hour < 10)
cout << "0";
cout << hour << ":";
}
if (minute < 10)
cout << "0";
cout << minute << ":";
if (second < 10)
cout << "0";
cout << second;
if (afternoon)
cout << " PM" << endl;
else
cout << " AM" << endl;
}
void Time::print_24()
{
if (hour < 10)
cout << "0";
cout << hour << ":";
if (minute < 10)
cout << "0";
cout << minute << ":";
if (second < 10)
cout << "0";
cout << second << endl;
}
Time Time::operator+(Time & t)
{
Time temp = *this;
for (int i = 0; i < t.second; i++)
{
temp.second += 1;
if (temp.second == 60)
{
temp.minute += 1;
if (temp.minute == 60)
{
temp.hour += 1;
temp.minute = 0;
}
temp.second = 0;
}
}
for (int i = 0; i < t.minute; i++)
{
temp.minute += 1;
if (temp.minute == 60)
{
temp.hour += 1;
temp.minute = 0;
}
}
temp.hour += t.hour;
return temp;
}
Time Time::operator-(Time & t)
{
Time temp = *this;
temp.hour -= t.hour;
for (int i = 0; i < t.minute; i++)
{
temp.minute -= 1;
if (temp.minute < 0)
{
temp.hour -= 1;
temp.minute = 59;
}
}
for (int i = 0; i < t.second; i++)
{
temp.second -= 1;
if (temp.second < 0)
{
temp.minute -= 1;
if (temp.minute < 0)
{
temp.hour -= 1;
temp.minute = 59;
}
temp.second = 59;
}
}
return temp;
}
Time Time::operator+(int s)
{
Time temp = *this;
for (int i = 0; i < s; i++)
{
temp.second += 1;
if (temp.second == 60)
{
temp.minute += 1;
if (temp.minute == 60)
{
temp.hour += 1;
temp.minute = 0;
}
temp.second = 0;
}
}
return temp;
}
Time Time::operator-(int s)
{
Time temp = *this;
for (int i = 0; i < s; i++)
{
temp.second -= 1;
if (temp.second < 0)
{
temp.minute -= 1;
if (temp.minute < 0)
{
temp.hour -= 1;
temp.minute = 59;
}
temp.second = 59;
}
}
return temp;
}
Time operator+(int s, Time & t)
{
return t + s;
}
Time operator-(int s, Time & t)
{
return t - s;
}
int main()
{//主函数设计如下，请勿修改.
Time t1(2, 34), t2, t3;
t2.SetTime(13, 23, 34);
cout << "t1+t2:";
t3 = t1 + t2;//两个Time类对象相加
t3.print_24();
cout << "\nt1+65:";
t3 = t1 + 65;//Time类对象加上65秒#
t3.print_24();
cout << "\n65+t1:";
t3 = 65 + t1;//65秒加上Time类对象#
t3.print_24();
cout << "\nt2-t1:";
t3 = t2 - t1;//两个Time类对象相减
t3.print_24();
cout << "\nt1-70:";
t3 = t1 - 70;//Time类对象减去70秒
t3.print_24();
return 0;
}
| 5. | 运算符的重载 【问题描述】不允许修改主函数，请将以下代码补充完整。 int main( ) 【样例输入】 |
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#include
using namespace std;
class String
{
char *ptr;
public:
String()
{
ptr=NULL;
}
String(char *s)
{
ptr=new char[strlen(s)+1];
strcpy(ptr, s);
}
~String()
{
delete []ptr;
}
void operator +=(const String &s);
String& operator =(const String &s);
friend ostream & operator <<(ostream &out, String &s);
void print()
{
cout<