c++实践课（上课用）

源程序：

//编写一个程序，将从键盘输入的n个字符串保存在一个一维数组A中。在输入字符串之前，先输入n的值。
//要求，数组A需要动态申请空间，程序运行结束前再释放掉。
//再输出n字符串中最长和最短的串，计算平均字符中的长度。

#include <iostream>
#include <string>
using namespace std;

int main()
{
int n, i, length = 0;
cout << "输入几个字符串：";
cin >> n;

string* A = new string[n];
string* p;
p = A; //指针p指向字符串数组A

cout << "请输入字符串：";
for (i = 0; i < n; i++)
{
cin >> A[i];
length = length + A[i].length(); //n个字符串的总长度
}

p = A; //让p重新指向字符串数组的首地址

string max = A[0];
string min = A[0];
for (i = 1; i < n; i++)
{
if (p[i].length() > max.length())
max = p[i];
if (p[i].length() < min.length())
min = p[i];
}

cout << "最长的字符串为：" << max << "\n" << "最短的字符串为：" << min << endl;
cout << "字符串的平均长度为：" << length / n << endl;

delete[]p;

return 0;
}

--------------------------------------------------------------------------------------------------------------------

//函数重载
#include <iostream>
using namespace std;

int bigger(int x, int y)
{
if (x > y)
return x;
else
return y;
}

float bigger(float x, float y)
{
if (x > y)
return x;
else
return y;
}

double bigger(double x, double y)
{
if (x > y)
return x;
else
return y;
}

int main()
{
int xI = 10, yI = 20;
float xF = 30, yF = 40;
double xD = 50, yD = 60;
cout << bigger(xI, yI) << endl;
return 0;
}

------------------------------------------------------------------------

//类内声音，类外定义
#include <iostream>
using namespace std;

class A
{
public:
int fun(double); //函数的声明
int fun(int);
};

int A::fun(double x)
{
return (int)x / 2;
}

int A::fun(int x)
{
return x * 2;
}

int main()
{
A a;
int s = a.fun(6.0) + a.fun(2);
cout << s << endl;
return 0;
}

-------------------------------------------------------------------------

#include <iostream>
using namespace std;

int main()
{
int* p1;
int** p2 = &p1;
int b = 20;
p1 = &b;
cout << *(*p2) << endl;
return 0;
}

----------------------------------------------------------------------------

#include<iostream>
#include<string>
using namespace std;

class Test{
int a, b;
int getmin()
{
return (a < b ? a : b);
}
public:
int c;
void setValue(int x1, int x2, int x3){
a = x1;
b = x2;
c = x3;
}
int GetMin();
};
int Test::GetMin(){
int d = getmin();
return (d = d < c ? d : c);
}
int main(){
Test t1;
t1.setValue(34, 6, 2);
cout <<"最小值为："<< t1.GetMin() << endl;
system("pause");
return 0;
}

--------------------------------------------------------------------------

#include <iostream>
using namespace std;

class myComplex
{
private:
double real, imag; //复数的实部和虚部
public:
myComplex(); //缺省的构造函数
myComplex(double r, double i);
friend myComplex addCom(myComplex c1, myComplex c2); //友元函数，复数相加
friend void outCom(myComplex c); //输出函数
};

myComplex::myComplex()
{
real = 0;
imag = 0;
}
myComplex::myComplex(double r, double i)
{
real = r;
imag = i;
}

myComplex addCom(myComplex c1, myComplex c2)
{
return myComplex(c1.real + c2.real, c1.imag + c2.imag);
}

void outCom(myComplex c)
{
cout << "(" << c.real << "," << c.imag << ")";
}

int main()
{
myComplex c1(1, 2), c2(3, 4), result;
result = addCom(c1, c2);
outCom(c1);
cout << "+";
outCom(c2);
cout << "=";
outCom(result);
cout << endl;
return 0;
}

-----------------------------------------------------------------------------------------

#include <iostream>
using namespace std;

class Point
{
private:
double x, y; //横坐标，纵坐标
friend class Line; //友元类
public:
Point(double i = 0,double j = 0)
{
x = i;
y = j;
}
Point(Point& p) //复制的构造函数
{
x = p.x;
y = p.y;
}
};

class Line
{
private:
Point p1, p2;
public:
Line(Point& xp1, Point& xp2) :p1(xp1), p2(xp2)
{}
double GetLength();
};

double Line::GetLength()
{
double dx = p2.x - p1.x;
double dy = p2.y - p1.y;
return sqrt(dx*dx+dy*dy);
}
int main()
{
Point p1, p2(6,8);
Line L1(p1, p2);
cout << L1.GetLength() << endl;
return 1;
}

---------------------------------------------------------------------

#include <iostream>
using namespace std;

class Point
{
private:
float x;
public:
void f(float a)
{
x = a;
}
void f()
{
x = 0;
}
friend float max(Point& a, Point& b); //程序填空
};

float max(Point& a, Point& b)
{
return (a.x > b.x) ? a.x : b.x;
}
int main()
{
Point a, b;
a.f(2.2);
b.f(3.3);
cout << max(a, b) << endl; //程序填空
return 0;
}

----------------------------------------------------------------------------

//下面程序定义了类Test，num的初值是5，程序创建对象t,且修改其num的值为10，使用show()函数
//输出num的值，请将程序补充完整.
#include <iostream>
using namespace std;

class Test
{
private:
static int num; //静态变量，应该在类的外面，由类来初始化
public:
Test(int);
void show();
};

int Test::num = 5; //程序填空
Test::Test(int n)
{
num = n;
}

void Test::show()
{
cout << num<<endl;
}

int main()
{
Test t(10);
t.show(); //程序填空
return 0;
}