رجآآآآء مساعده في ال linked list

ارجوكم ياخواني عندي برنامج مكتوب بلغة الc++ وعو عباره عن القوائم المرتبطه linked list هناك اكواد في البرنامج لم استطع فهمها ساضع البرنامج كاملا لكن لاريد شرحهه كاملا فقط بعضه وسأعرضه لكم

  #include<iostream>
#include<conio.h>
#include<stdlib.h>
#include<process.h>
using namespace std;

class list
{
	struct node
	{
		int data;
		node *link;
	}*p;
public:
	void inslast(int);
	void insbeg(int);
	void insnext(int,int);
	void delelement(int);
	void delbeg();
	void dellast();
	void disp();
	int seek(int);
	list(){
              p=NULL;
              }
	~list();
};

void list::inslast(int x)
{
	node *q,*t;
	if(p==NULL)
	{
		p=new node;
		p->data=x;
		p->link=NULL;
	}
	else
	{
		q=p;
		while(q->link!=NULL)
			q=q->link;
		t=new node;
		t->data=x;
		t->link=NULL;
		q->link=t;
	}
	cout<<"Inserted successfully at the end.";
	disp();
}

void list:: insbeg(int x)
{
	node *q;
	q=p;
	p=new node;
	p->data=x;
	p->link=q;
	cout<<" Inserted successfully at the begining..";
	disp();
}


void list::delelement(int x)
{
	node *q,*r;
	q=p;
	if(q->data==x)
	{
		p=q->link;
		delete q;
		return;
	}
	r=q;
	while(q!=NULL)
	{
		if(q->data==x)
		{
			r->link=q->link;
			delete q;
			return;
		}
		r=q;
		q=q->link;
	}
	cout<<" Element u entered   "<<x<<"    is not found..";
}

void list:: delbeg()
{
	cout<<"The list before deletion:";
	disp();
	node *q;
	q=p;
	if(q==NULL)
	{
		cout<<"No data is present..";
		return;
	}
	p=q->link;
	delete q;
	return;
}


void list:: dellast()
{
	cout<<"The list before deletion:";
	disp();
	node *q,*t;
	q=p;
	if(q==NULL)
	{
		cout<<"There is no data in the list..";
		return;
	}
	if(q->link==NULL)
	{
		p=q->link;
		delete q;
		return;
	}

	while(q->link->link!=NULL)
		q=q->link;
	q->link=NULL;
	return;
}

list::~list()
{
	node *q;
	if(p==NULL) return;
	while(p!=NULL)
	{
		q=p->link;
		delete p;
		p=q;
	}
}

void list::disp()
{
	node *q;
	q=p;
	if(q==NULL)
	{
		cout<<"No data is in the list..";
		return;
	}
	cout<<"The items present in the list are :";
	while(q!=NULL)
	{
		cout<<"	"<<q->data;
		q=q->link;
	}
}

void list :: insnext(int value,int position)
{
	node *temp,*temp1;
	temp=p;
	if(temp1==NULL)
	{
		temp1= new node;
		temp1->data=value;
		temp1->link=NULL;
		p=temp1;
		return;
	}
	for(int i=0;((i<position)&&(temp->link!=NULL)) ;i++)
	{
		if(i==(position-1))
		{
			temp1= new node;
			temp1->data= value;
			temp1->link=temp->link;
			temp->link=temp1;
		}
		temp=temp->link;
	}
	cout<<"Inserted successfully at the position.."<<position;
	disp();
}


int list::seek(int value)
{
	node *temp;
	temp=p;
	int position=0;
	while(temp!=NULL)
	{
		if(temp->data==value)
			return position+1;
		else
		{
			temp=temp->link;
			position=position+1;
		}
	}
	cout<<"Element "<<value<<" not found";
	return 0;
}
void main()
{
list l;
int ch,v,p,ps;
do
{

	cout<<"Operations on List..";
	cout<<"1.Insertion2.Deletion3.Display4.Seek5.Exit";
	cout<<"Enter ur choice:";
	cin>>ch;

	switch(ch)
	{
	case 1:
		cout<<"1.Insertion at begining2.Insertion at the end";
		cout<<"3.Insertion after the mentioned position";
		cout<<" Enter ur choice:";
		cin>>ps;
		cout<<"Enter the value to insert:";
		cin>>v;
		switch(ps)
		{
			case 1:
				l.insbeg(v);
				break;
			case 2:
				l.inslast(v);
				break;
			case 3:
				cout<<"Enter the position to insert the value:";
				cin>>p;
				l.insnext(v,p);
				break;

			default:
				cout<<" The choice is invalid";
				return;
		}
	break;

	case 2:
		cout<<"1.Delete the first element 2.Delete the last element";
		cout<<"3.Enter the element to delete from the list";
		cout<<"Enter ur choice:";
		cin>>ps;
		switch(ps)
		{
			case 1:
				l.delbeg();
				cout<<"The list after deletion:";l.disp();
				break;
			case 2:
				l.dellast();
				cout<<"The list after deletion:";l.disp();
				break;
			case 3:
				l.disp();
				cout<<"Enter the element to delete :	";
				cin>>v;
				l.delelement(v);
				cout<<"The list after deletion:";l.disp();
				break;

			default:
				cout<<"The option is invalid..";
				break;
		}
	break;

	case 3:
		l.disp();
		break;

	case 4:
		l.disp();
		cout<<"Enter the element to search:";
		cin>>v;
		cout<<"The position of the element "<< v<<"  is "<<l.seek(v);
		getch();
		break;

	case 5:
		exit(1);

	default:
		cout<<"The option is invalid...";
		return;
	}
	getch();
}while(ch!=5);
getch();
return;
}

أنا فقط اريد شرح هذا

 void list::delelement(int x)
{
	node *q,*r;
	q=p;
	if(q->data==x)
	{
		p=q->link;
		delete q;
		return;
	}
	r=q;
	while(q!=NULL)
	{
		if(q->data==x)
		{
			r->link=q->link;
			delete q;
			return;
		}
		r=q;
		q=q->link;
	}
	cout<<" Element u entered   "<<x<<"    is not found..";
}

وأيضا هذا الكود

 void list:: dellast()
{
	cout<<"The list before deletion:";
	disp();
	node *q,*t;
	q=p;
	if(q==NULL)
	{
		cout<<"There is no data in the list..";
		return;
	}
	if(q->link==NULL)
	{
		p=q->link;
		delete q;
		return;
	}

	while(q->link->link!=NULL)
		q=q->link;
	q->link=NULL;
	return;
}

list::~list()
{
	node *q;
	if(p==NULL) return;
	while(p!=NULL)
	{
		q=p->link;
		delete p;
		p=q;
	}

وهذا الكود

 void list :: insnext(int value,int position)
{
	node *temp,*temp1;
	temp=p;
	if(temp1==NULL)
	{
		temp1= new node;
		temp1->data=value;
		temp1->link=NULL;
		p=temp1;
		return;
	}
	for(int i=0;((i<position)&&(temp->link!=NULL)) ;i++)
	{
		if(i==(position-1))
		{
			temp1= new node;
			temp1->data= value;
			temp1->link=temp->link;
			temp->link=temp1;
		}
		temp=temp->link;
	}
	cout<<"Inserted successfully at the position.."<<position;
	disp();
}

فقط الثلاث دوال السابقه اريد شرحها من البرنامج السابق ,,,, ارجوكم لاتخيبوا ظني بكم :cry: :cry: :cry: :cry: