练习.txt

钱能主编 C++程序设计教程（第一版） 该书习题的答案代码

10.1
#include <iostream.h>

struct math
{
	float mid;
	float fina;
};

void main()
{
	math stu1;
	cout<<"input the mid-term and final-term scores:"<<endl;
	cin>>stu1.mid>>stu1.fina;

	cout<<"the average scores is:"<<(stu1.mid+stu1.fina)/2<<endl;
}

10.2
#include <iostream.h>
#include <string.h>
#include <math.h>

struct person
{
	char name[20];
	person* next;
};

void insert(person* (&head));

void main()
{
	person staff[5];
	person* head=staff;
	for(int i=0;i<5;i++)
	{
		cin>>staff[i].name;
		if(i<4)
		{
			staff[i].next=&(staff[i+1]);
		}
		else
			staff[i].next=NULL;
	}
	cout<<endl;

	insert(head);

	cout<<endl<<"in main..."<<endl;
	while(head->next!=NULL)
	{
		cout<<head->name<<endl;
		head=head->next;
	}
	cout<<head->name<<endl;
}

void insert(person* (&head))
{
	person* pCurrent=head;
	person* pivot=head;
	person* m=new person;
	cout<<"input the name to be added:"<<endl;
	cin>>m->name;
	
	char* p1=pCurrent->name;
 	char* p2="jone";

	//first situation
	if(!strcmp(p1,p2))   
	{
		cout<<"the first situation."<<endl;
		m->next=head;
		head=m;
		return;
	}

	pivot=pCurrent;
	pCurrent=pCurrent->next;
	p1=pCurrent->name;
	//注意让while循环的条件，若以strcmp()为条件，则出现-1情况，
	//故本题采用fabs(strcmp(p1,p2))；另外注意不能用!strcmp()为条件，这样与预想相反
	//注意：p1若不在循环里给其赋值的话，始终指向第一个结构元素的name，这样结果永远都是一样！
	while(fabs(strcmp(p1,p2))&&pCurrent->next!=NULL)  
	{
		pivot=pCurrent;
		pCurrent=pCurrent->next;
		p1=pCurrent->name;
	}
	//cout<<"testing... "<<pCurrent->name<<endl;

	if(pCurrent->next==NULL)
	{
		cout<<"the end situation."<<endl;
		m->next=NULL;
		pCurrent->next=m;
		return;
	}
	if(!strcmp(p1,p2))
	{
		cout<<"the mid situation."<<endl;
		m->next=pivot->next;
		pivot->next=m;
		return;
	}
	cout<<"error!"<<endl;
}

10.3
#include <iostream.h>

struct data
{
	long int ele;
	data* next;
};

void inverse(data* (&head));

void main()
{
	//initialize a linked list
	data ori[4];
	for(int i=0;i<4;i++)
	{
		cin>>ori[i].ele;
		if(i<3)
			ori[i].next=&(ori[i+1]);
		else
			ori[i].next=NULL;
	}
	
	//initialize the head of linked list
	data head=
	{20041302,ori};
	head.next=ori;
	data* tmp=&head;

	inverse(tmp);

	cout<<"after changing..."<<endl;
	i=0;
	while(tmp->next!=NULL)
	{
		cout<<tmp->ele<<endl;
		tmp=tmp->next;
	}
	cout<<tmp->ele<<endl;
}

void inverse(data* (&head))
{
	data* tmp=head;
	data* p[4];

	//reorder
	for(int i=3;i>=0;i--)
	{
		p[i]=tmp->next;
		tmp=p[i];
	}
	//reindirection
	for(i=0;i<3;i++) p[i]->next=p[i+1];
	p[3]->next=NULL;
	head->next=p[0];
}

10.4
#include <iostream.h>

struct Lnode
{
	double data;
	Lnode* next;
};

void ShowList(Lnode* list)
{
	cout<<"Func:ShowList:"<<endl;
	while(list!=NULL)
	{
		cout<<list->data<<endl;
		list=list->next;
	}
	cout<<"Func End."<<endl;
}

void AddToEnd(Lnode* newl,Lnode* (&head))
{
	Lnode* tmp=head;
	if(head==NULL)
	{
		head=newl;
		return;
	}
	while(tmp->next!=NULL)
		tmp=tmp->next;
	tmp->next=newl;
}

Lnode* GetNode()
{
	Lnode* item;
	item=new Lnode;
	if(item)
	{
		item->next=NULL;
		item->data=0.0;
	}
	else
		cout<<"Nothing allocated."<<endl;
	return item;
}

void DeleteList(Lnode* head)  //高！
{
	while(head!=NULL)
	{
		Lnode* p;
		p=head;
		head=head->next;
		delete p;
	}
}

void main()
{
	Lnode* head=NULL;
	Lnode* temp;
	temp=GetNode();
	while(temp)
	{
		cout<<"data?";
		cin>>temp->data;

		if(temp->data>0)
			AddToEnd(temp,head);
		else             //once input a negative, the program exit.
			break;
		temp=GetNode();  //continue to get next node
	}

	ShowList(head);
	DeleteList(head);
}

10.5
#include <iostream.h>

struct list
{
	int num;
	list* next;
};

list l1[3]=
{{21,&l1[1]},{22,&l1[2]},{23,NULL}};

list l2[3]=
{{31,&l2[1]},{32,&l2[2]},{33,NULL}};

void showlist(list* head)
{
	while(head!=NULL)    //注：此处亦可写成while(head);
	{
		cout<<head->num<<endl;
		head=head->next;
	}
}

void link(list* &head1,list* head2)
{
	list* h_tmp=head1;
	while(h_tmp->next!=NULL)
		h_tmp=h_tmp->next;
	h_tmp->next=head2;
}

void main()
{
	list* head1=&l1[0];
	list* head2=&l2[0];
	link(head1,head2);
	showlist(head1);
}

10.6
#include <iostream.h>

struct stud
{
	long int ID_num;
	char name[20];
	char gender;
	int  age;
	stud* next;
};

stud pupil[8]=
{
	{10031,"daniel",'m',12,&pupil[1]},
	{10038,"ryu",'m',12,&pupil[2]},	
	{10037,"ruby",'m',11,&pupil[3]},
	{10034,"kevin",'m',12,&pupil[4]},	
	{10032,"cathy",'f',11,&pupil[5]},
	{10033,"lily",'f',12,&pupil[6]},
	{10036,"kate",'f',11,&pupil[7]},
	{10035,"ken",'m',12,NULL}
};

void show(stud* head)
{
	while(head)
	{
		cout<<head->name<<endl;
		head=head->next;
	}
}

void isort(stud* (&head),int size);

void main()
{
	int n=8;
	stud* head=pupil;
	isort(head,n);
	show(head);
}

void isort(stud* (&a),int size)
{
	//stud* a=head;
	stud  inserter;
	stud* tmp;
	int index;

	for(int i=1;i<size;i++)
	{
		inserter=a[i];
		index=i-1;
		while(index>=0 && inserter.ID_num<a[index].ID_num)
		{
			tmp=a[index+1].next;
			a[index+1]=a[index];
			a[index+1].next=tmp;  //to protect the next pointer of a[index+1]
			index--;
		}
		tmp=a[index+1].next;      //protect the a[index+1].next
		a[index+1]=inserter;
		a[index+1].next=tmp;
	}
}