[andrei solovjev]

Всем спасибо. Класс написал, вот код, если кому интересно:

#include <iostream.h>

const SIZE = 100;

struct Item {
	float x;
	float y;
	int n;
};

class O {
private:
	Item a[SIZE];
	void create(Item &x) {x.n = 0;}
public:
	O();
	O(float[],float[],int);
	O operator+=(Item);
	void show(int) ;
	void center(int);
	void povorot(int, int, float, float);
	void peremeshenie(int, float, float);
	void operator [] (int);
	friend ostream& operator<<(ostream&, O&);
	friend istream& operator>>(istream&, O&);
	};

O::O() {
	for (int i = 0; i < SIZE; i++) create(a[i]);
}
O::O(float x1[], float y1[], int num) {
	for (int i = 0; i < num; i++){
		a[i].x=x1[i];
		a[i].y=y1[i];
		a[i].n=num;
	}
}

void O::show(int num){
	cout<<endl<<"Mnogougolnik s vershinami:\n";
	for (int i=0; i<num; i++){
		cout<<"("<<a[i].x<<","<<a[i].y<<"), ";
	}
}

void O::center(int num){
	cout<<endl<<"Mnogougolnik s koordinatami centra tyazesti:\n";
	float x=0,y=0;
	for (int i=0; i<num; i++){
		x=x+a[i].x;
		y=y+a[i].y;
	}
	x=x/num;
	y=y/num;
	cout<<"("<<x<<","<<y<<")"<<endl;
}

void O::povorot(int num, int ugol, float x, float y){
	float q,w;
		for (int i=0;i<num;i++){
			if (ugol==90){
				q=x+(y-a[i].y);
				w=y+(a[i].x-x);
				cout<<"("<<q<<","<<w<<") ";
			}
			if (ugol==180){
				q=x+(x-a[i].x);
				w=y+(y-a[i].y);
				cout<<"("<<q<<","<<w<<") ";
			}
			if (ugol==270){
				q=x+(a[i].y-y);
				w=y+(x-a[i].x);
				cout<<"("<<q<<","<<w<<") ";
			}
		}
}


void O::peremeshenie(int num, float x, float y){
	for (int i=0; i<num; i++)
		//float q=a[i].x+x, w=
	cout<<"("<<a[i].x+x<<","<<a[i].y+y<<") ";
}


void O::operator [] (int num){
	cout<<"("<<a[num].x<<","<<a[num].y<<") ";
}

O O::operator +=(Item item){
	for (int i=0; i<SIZE; i++){
		if (a[i].n==-858993460||a[i].n==0) {
			a[i]=item;
			break;
		}
	}
	return *this;
}

ostream& operator<<(ostream& os, O& P){
	for (int i=0; i<SIZE; i++){
		if (P.a[i].n>0){
			os<<"("<<P.a[i].x<<","<<P.a[i].y<<"), ";}
	}
	return os;
}

istream& operator>>(istream& is, O& P){
	Item item;
	int kol=0;
	cout<<"Please, enter number of corners:\n"<<"->";
			cin>>kol;
			cout<<"Please, enter a kordinati\n";
			for (int i=0;i<kol;i++){
				cout<<"Enter a "<<i<<" koord x\n"<<"->";
				cin>>item.x;
				cout<<"Enter a "<<i<<" koord y\n"<<"->";
				cin>>item.y;
				item.n=kol;
				P+=item;
			}
			cout<<"New mnogoug sformirovan\n";
			return is;
}



void main() {
	int choice, choise2=-1;
	O P;
	Item item;
	    	int kol=0;
			float xx[SIZE], yy[SIZE], povorot_x, povorot_y, rv_x,rv_y;
			int i=0;
	do {
		
	    cout<<"\nPlease, select a choise"<<endl;
		cout << "1.New"<<endl<<"2.Add a mnogoug"<<endl<<"3.Vivod koordinat\n"<<"4.Opredelenie centra tyazesti\n"<<"5.Povorot figuri na ugol kratnii 90\n"<<"6.Peremeshenie\n"<<"7.Vivod koordinat vershin\n"<<"8.Dobavlenie tochki (+=)\n";
        cout<<"9.Exit\n";
		cin >> choice;
		cout << endl;
		switch (choice) {
		case 1:
			P = O();
	        cout<<"New pustoy mnogoug is created"<<endl;
			break;
			//////////////////
		case 2:
			cin>>P;
			break;
			/////////////////////////
			case 3:
				//P.show(kol);
				cout<<P;
			break;
			////////////////////////
			case 4:
				P.center(kol);
			break;
			////////////////////////
			case 5:
				cout<<"Vvedite koordinati tochki, otnositelno kotoroy nuzno osushestvit povorot\n";
				cout<<"X=";
				cin>>povorot_x;
				cout<<"Y=";
				cin>>povorot_y;
				cout<<"Viberite ugol:\n1.90 gradusov\n2.180 gradusov\n3.270 gradusov\n";
				cin>>choise2;
				switch (choise2) {
		          case 1:
				    cout<<"1.90 gradusov"<<endl;
			
					P.povorot(kol,90,povorot_x,povorot_y);
			      break;
				  ////////
		          case 2:
				    cout<<"2.180 gradusov"<<endl;
					P.povorot(kol,180,povorot_x,povorot_y);
			      break;
				  ////////
		          case 3:
				    cout<<"3.270 gradusov"<<endl;
					P.povorot(kol,270,povorot_x,povorot_y);
			      break;
				  ////////
				}
			break;
			/////////////////////////
			case 6:
				cout<<"Peremeshenie na radius-vector\nVvedite koordinati radius-vectora:\nX=";
				cin>>rv_x;
				cout<<"Y=";
				cin>>rv_y;
				P.peremeshenie(kol,rv_x,rv_y);
			break;
			////////////////////////
			case 7:
				cout<<"Vvedite nomer vershini\n->";
				cin>>rv_x;
				P[rv_x];
			break;
			////////////////////////
			case 8:
			cout<<"Please, enter a kordinati\n X=";
				cin>>item.x;
				cout<<"Y=";
				cin>>item.y;
				item.n=1;
			P+=item;
			kol++;
			break;
		
		
		}
	}
			while (choice != 9);
	
}