pointer.cpp

这我们老师对是面向对象程序设计（清华大学出版社）一书制作的PPT

	int choice;
	fp fun[]={menu1,menu2,menu3};
	do{
		cout<<"1——display good\n"
			<<"2——display better\n"
			<<"3——display best\n"
			<<"0——exit\n"
			<<"Enter your choice:";
		cin>>choice;
		switch(choice){
		case 1:fun[0]();break;
		case 2:fun[1]();break;
		case 3:fun[2]();break;
		case 0:break;
		default:cout<<"You entered a wrong key.\n\n";
		}

	}while(choice);
}


//【例6.28】设计一个程序，计算在某个范围内，步长为0.1的所有点的三角函数值的和。


#include <math.h>
double sigma(double (*fp)(double),double start,double end)
{
	double temp=0.0;
	for(double d=start;d<end;d+=0.1)
		temp+=fp(d);
	return temp;
}

void main6_28()
{
	double sum;
	sum=sigma(sin,0.1,1.0);
	cout<<"从0.1到1.0之间(步长为0.1)所有点的正弦值之和为："<<sum<<'\n';
	sum=sigma(cos,1.0,3.0);
	cout<<"从0.1到1.0之间(步长为0.1)所有点的余弦值之和为："<<sum<<'\n';
}

//【例6.29】用梯形法求定积分：


#include <math.h>

float fun1(float x)
{
	return x+sin(x);
}

float fun2(float x)
{
	return 2*x/(1+x*x);
}

float fun3(float x)
{
	return (2*x+x*x)/(1+x+cos(x));
}

float integ(float (*fp)(float),float x1,float x2,float n)
{
	float sum,h;
	sum=(fp(x1)+fp(x2))/2;
	h=(x2-x1)/n;
	for(int i=1;i<n;i++) sum+=fp(x1+i*h);
	return sum*h;
}

void main6_29()
{
	cout<<"积分integal1="<<integ(fun1,1,4,1000)<<'\n';
	cout<<"积分integal2="<<integ(fun2,-1,4,1000)<<'\n';
	cout<<"积分integal3="<<integ(fun3,2,5,1000)<<'\n';
}


//【例6.30】内存的动态分配和撤消


void main6_30()
{
	int *p1,(*p2)[8];
	float *p3;
	char *p4;
	float *p5=new float(2.5);
	int *p6;

	p1=new int(2);
	cout<<*p1<<'\n';
	
	p2=(int (*)[8])new int[8];
	p2=new int[1][8];
	for(int i=0;i<8;i++)
		(*p2)[i]=i+1;
	for(i=0;i<8;i++)
		cout<<(*p2)[i]<<'\t';
	cout<<'\n';

	p3=new float;
	*p3=5.2;
	cout<<*p3<<'\n';

	p4=new char[10];
	strcpy(p4,"abcdefg");
	cout<<p4<<'\n';

	cout<<*p5<<'\n';

	int c=10;
	p6=new int[c];
	for(i=0;i<c;i++)
		p6[i]=2*i;
	for(i=0;i<c;i++)
		cout<<p6[i]<<'\t';
	cout<<'\n';

	delete p1;
	delete p2;
	delete p3;
	delete [10]p4;
	delete p5;
	delete [c]p6;

	p1=new int(6);
	cout<<*p1<<'\n';
	delete p1;

	int (*p)[10]=new int[3][10];
	delete p;

}


//【例6.31】为结构类型的指针动态分配内存空间。

struct node
{
	int x;
	float y;
	char z[10];
};

void main6_31()
{
	node *pn;
	pn=new node;
	pn->x=2;
	pn->y=4.3;
	strcpy(pn->z,"China!");
	cout<<pn->x<<'\t'<<pn->y<<'\t'<<pn->z<<'\n';
	delete pn;
	

}


//【例6.32】引用类型变量的定义及使用


void fun()
{
	int i=10;
	static int &j=i;
	j++;
	cout<<j<<'\n';
}

void main6_32()
{
	float k,&ref=k;
	k=100.0;
	cout<<"&k:"<<&k<<"\t&ref:"<<&ref<<'\n';
	cout<<"k="<<k<<"\tref="<<ref<<'\n';
	ref+=200;
	cout<<"k="<<k<<"\tref="<<ref<<'\n';

	float l=500.0;
	ref=l;
	cout<<"k="<<k<<"\tref="<<ref<<"\tl="<<l<<'\n';
	cout<<"&k:"<<&k<<"\t&ref:"<<&ref<<"\t&l:"<<&l<<'\n';
	
	fun();
	fun();	
}


//【例6.33】用引用作为函数参数的方法实现例6.18中函数swap()的功能。


void swap(int &x,int &y)
{
	int temp;
	temp=x;
	x=y;
	y=temp;
}

void main6_33()
{
	int a=2,b=4;
	cout<<"a="<<a<<"\tb="<<b<<'\n';
	swap(a,b);
	cout<<"a="<<a<<"\tb="<<b<<'\n';
}


//【例6.34】结构类型的引用作为函数的形参。


struct student
{
	char name[10];
	int age;
	long id;
	char address[50];
};

void input(student &stu)
{
	cout<<"请输入姓名、年龄、学号和住址：\n";
	cin>>stu.name>>stu.age>>stu.id>>stu.address;
}

void output(student stu)
{
	cout<<"name="<<stu.name<<"\tage="<<stu.age
		<<"\tid="<<stu.id<<"\taddress="<<stu.address<<'\n';
}

void main6_34()
{
	student stu;
	input(stu);
	output(stu);
}


//【例6.35】函数返回值为引用类型应用举例


int number1;

int &set1()
{
	return number1;
}

int &set2()
{
	static int number2;
	return number2;
}

int &max(int &m,int &n)
{
	return (m>n?m:n);
}


void main6_35()
{
	set1()=5;
	cout<<set1()<<'\t'<<number1<<'\n';
	number1=7;
	cout<<set1()<<'\t'<<number1<<'\n';
	
	set2()=6;
	int a=set2();
	cout<<a<<'\n';

	int b=3,c=4;
	cout<<max(b,c)<<'\n';
	max(b,c)=2;
	cout<<"b="<<b<<"\tc="<<c<<"\tmax(b,c)="<<max(b,c)<<'\n';
	max(b,c)=10;
	cout<<"b="<<b<<"\tc="<<c<<"\tmax(b,c)="<<max(b,c)<<'\n';
}

//【例6.36】void指针与其它类型指针的关联。

void main6_36()
{
	void *pv1,*pv2;
	float *pf;
	int *pi=new int;
	
	pv1=pi;	
	*pi=2;
	cout<<*(int *)pv1<<'\n';
	*(int *)pv1=5;
	cout<<*pi<<'\n';

	pf=(float *)pv2;

}


//【例6.37】void指针作为函数的参数。

int cmpInt(void *a,void *b)
{
	return *(int *)a-*(int *)b;
}

int cmpFloat(void *a,void *b)
{
	return *(float *)a-*(float *)b>0?1:-1;
}

int cmpChar(void *a,void *b)
{
	return strcmp((char *)a,(char *)b);
}

void  Sort(void *v,int n,int size,int(*com)(void *,void *))
{
	int i,j,k;
	char *p,*q,t;
	for(i=0;i<n-1;i++){
		p=(char *)v+i*size;
		for(j=i+1;j<n;j++){
			q=(char *)v+j*size;
			if(com(p,q)>0)
				for(k=0;k<size;k++){
					t=p[k];p[k]=q[k];q[k]=t;
				}
		}
	}
}

void main6_37()
{
	int vi[]={34,12,25,43,8,16};
	float vf[]={34.2,23.1, 67.4, 8.9,14.8};
	char vc[][10]={"NanJing","BeiJing","WuHan","ShengYang"};
	int i;
	Sort(vi,sizeof(vi)/sizeof(int),sizeof(int),cmpInt);
	for(i=0;i<sizeof(vi)/sizeof(int);i++)
		cout<<vi[i]<<'\t';
	cout<<'\n';
	Sort(vf,sizeof(vf)/sizeof(float),sizeof(float),cmpFloat);
	for(i=0;i<sizeof(vf)/sizeof(float);i++)
		cout<<vf[i]<<'\t';
	cout<<'\n';
	Sort(vc,4,10,cmpChar);
	for(i=0;i<4;i++)
		cout<<vc[i]<<'\t';
	cout<<'\n';
}


//【例6.38】指向常量的指针作为函数的参数。


void strcopy(char *to,const char * from)
{
	while(*to++=*from++);	
}

void main6_38()
{
	char a[20]="Hello,China!";
	char *b=new char[20];
	strcopy(b,a);
	cout<<b<<'\n';
	delete b;
}

//【例6.39】链表的创建与操作

typedef struct node1{
		int data1;
		char data2[10];
		node1 *next;
	}*ptrN;

ptrN createLinked()
{
	ptrN p1,p2,head;
	int a;
	char *ch=new char[20];
	head=0;
	cout<<"产生一条无序链表，请输入数据，以-1结束:\n";
	while(1){
		cin>>a;			
		if(a==-1)break;
		cin>>ch;
		p1=new node1;
		p1->data1=a;
		strcpy(p1->data2,ch);
		if(head==0){
			head=p1;p2=p1;
		}
		else{
			p2->next=p1;p2=p1;
		}
	
	}
	if(head)p2->next=0;
	delete ch;
	return head;
}

ptrN accessNode(const ptrN head,int n)
{
	ptrN tmpNode;
	if(head==0)
		return 0;
	else
		tmpNode=head;
	for(int i=0;i<n-1;i++)
	{
		if(tmpNode->next==0)
			return 0;
		tmpNode=tmpNode->next;
	}
	return tmpNode;
}

ptrN accessTrail(const ptrN head)
{
	ptrN tmpNode;
	if(head==0)
		return 0;
	else
		tmpNode=head;
	while(tmpNode->next)
		tmpNode=tmpNode->next;
	return tmpNode;
}

ptrN insertNode(ptrN head,ptrN newNode,int n)
{
	ptrN pPre,pBac;
	if(head==0)
	{
		head=newNode;
		head->next=0;
	}
	else if(n==1)
	{
		pBac=head;
		head=newNode;
		head->next=pBac;	
	
	}
	else{
		pPre=accessNode(head,n-1);
		if(pPre&&pPre->next)
		{
			pBac=pPre->next;
			pPre->next=newNode;
			newNode->next=pBac;
		}
		else
		{
			pPre=accessTrail(head);
			pPre->next=newNode;
			newNode->next=0;			
		}
	}
	return head;
}

ptrN deleteNode(ptrN head,int n)
{
	ptrN pCur,pPre,pBac;
	if(head==0)
		return 0;
	else if(n==1)
	{
		pCur=head;
		head=head->next;
		delete pCur;
	}
	else
	{
		pCur=accessNode(head,n);
		if(pCur&&pCur->next)
		{
			pPre=accessNode(head,n-1);
			pBac=(pPre->next)->next;
			pPre->next=pBac;
			delete pCur;
		}
		else if(pCur&&pCur->next==0)
		{
			pPre=accessNode(head,n-1);
			pPre->next=0;
			delete pCur;
		}
		else if(pCur==0)
		{
			cout<<"链表的结点数小于"<<n<<",没有要删除的结点!\n";
		}
	}
	return head;
}

void deleteLink(ptrN head)
{
	ptrN tmpNode;
	while(head)
	{
		tmpNode=head;
		head=head->next;
		delete tmpNode;
	}
}

ptrN insert_sort_node(ptrN head,ptrN newNode)
{
	ptrN pPre,pBac;	
	if(head==0)
	{
		head=newNode;
		head->next=0;
		return head;
	}
	else if(head->data1>newNode->data1)
	{
		newNode->next=head;
		head=newNode;
		return head;
	}
	pPre=head;
	while(pPre->next)
	{
		pBac=pPre->next;
		if(pPre->data1<=newNode->data1&&pBac->data1>newNode->data1)
		{
			pPre->next=newNode;
			newNode->next=pBac;
			return head;
		}
		pPre=pPre->next;
	}
	pPre->next=newNode;
	newNode->next=0;
	return head;
}

ptrN create_sort_linked()
{
	ptrN head=0,p1;
	int a;
	char *ch=new char[20];
	cout<<"产生一条有序链表，请输入数据，以-1结束:\n";
	while(1){
		cin>>a;
		if(a==-1)break;
		cin>>ch;
		p1=new node1;
		p1->data1=a;
		strcpy(p1->data2,ch);
		head=insert_sort_node(head,p1);
	}
	return head;

}

void outputNodes(const ptrN head)
{
	int i=1;
	ptrN nodeN;
	while(1)
	{
		nodeN=accessNode(head,i);
		if(nodeN)
			cout<<"第"<<i<<"个结点中的数据为："<<nodeN->data1<<'\t'<<nodeN->data2<<'\n';
		else
			break;
		i++;
	}
}

void outputNodes1(const ptrN head)
{
	ptrN nodeN;
	int i=1;
	nodeN=head;
	while(nodeN)
	{
		cout<<"第"<<i<<"个结点中的数据为："<<nodeN->data1<<'\t'<<nodeN->data2<<'\n';
		nodeN=nodeN->next;
		i++;
	}
	
}

void main6_39()
{
	/*
	cout<<"创建一个无序链表:\n";
	ptrN head=createLinked();
	cout<<"输出链表中的所有结点:\n";
	outputNodes(head);
	cin.get();
	
	cout<<"\n在链表中插入一个结点!\n";
	ptrN tmpNode=new node1;
	tmpNode->data1=2;
	strcpy(tmpNode->data2,"China!");
	head=insertNode(head,tmpNode,3);
	cout<<"\n输出链表中的所有结点:\n";
	outputNodes1(head);
	cin.get();

	cout<<"\n删除链表中的第2个结点:\n";
	head=deleteNode(head,2);
	cout<<"输出链表中的所有结点:\n";
	outputNodes1(head);
	
	cout<<"\n释放链表所占用的内存空间!";
	deleteLink(head);
*/
	ptrN head1=create_sort_linked();
	outputNodes(head1);
	deleteLink(head1);


}

//习题15

double root(double (*pf)(double x), double a,double b,int n)
{
	double c;
	for(int i=0;i<n;i++)
	{
		c=(a+b)/2;
		if(pf(a)*pf(c)<=0)
			b=c;
		else if(pf(c)*pf(b)<0)
			a=c;
		else
			cout<<"方程没有实根！\n";

	}
	return c;
}

double f(double x)
{
	return 2-x*x;
}

void main15()
{
	int x;
	cout<<root(f,1,2,1000)<<endl;
}


//实验题4


typedef struct node2
{
	int data, count;
	node2 *next;
}snode, *ptr;

void compress(ptr head)
{
	ptr p1,p2;
	p1=head;
	while(p1->next)
	{
	     p2=p1->next;
		if(p1->data==p2->data)
		{
			p1->count++;
			p1->next=p2->next;
			delete p2;
		}
		else(p1=p1->next) ;
	}
}

//实验题3

typedef int *IPTR;

int sequence(IPTR p,int n)
{
	int i=0;
	while(*p==*(p+1)&&i<n-1)p++,i++;
	if(i==n-1)return 3;
	if(*p<*(p+1))
	{
		for(;i<n-1;i++,p++)
			if(*p>*(p+1)) return 0;
		return 1;
	}
	else
	{
		for(;i<n-1;i++,p++)
			if(*p<*(p+1))  return 0;
			return 2;
	}
		
}

void mainex1()
{
	int a[10]={1,1,1,1,1,1,1,1,1,1};
	cout<<sequence(a,10)<<endl;
}

void mainex2()
{
	int (*p)[4]=new int[3][4];
	int (*p1)[4]=p;
	int *p2=p[1]+2;
	*p2=4;
	delete p;
	cout<<*p2<<endl;
}