int* tab = new( liczba_elementów );
(...)
delete tab;

int* tab = (int*)malloc( liczba_elementów * sizeof( int ) );
(...)
free( tab );

int* tab = (int*)calloc( liczba_elementów, sizeof( int ) );
(...)
free( tab );

int tab [], i , a;

cout<<"Podaj rozmiar tablicy ";
cin>>n;
cout<<"Podaj a ";
cin>>a;
tab[0]=a;
for(i = 1 ; i<n ; i++)
{
a=a-2;
tab[i]=a;
}

tab[0] = a;
i = 1
do
{
a=a-2;
tab[i] = a;
i++
}
while(i<n);

#include <stdio.h>;
#include <iostream>;




using namespace std;



int main()
{

	int tab[99999];
	int n , i , a ;
	cout<<"podaj n\n";
	cin>>n;
	cout<<"\npodaj a\n";
	cin>>a;


	tab[0] = a;
	cout<<"Element tablicy 1 = "<<tab[0];
	i = 1;
	do
	{
		a=a-2;
		tab[i] = a;
		cout<<"Element tablicy "<<i<< " = "<<tab[i];
		i++;
		

	}
	while(i<n);
	getchar();
	getchar();
	return 0;


}

#include <iostream>
#include <stdlib.h>

using namespace std;

int main()
{
	int i, a, n;
	cout << "podaj n: "<< endl;
	cin >> n;

	if ( n > 0 )
	{
		int* tab = (int*)calloc( n, sizeof( int ) );

		cout << "podaj a: "<< endl;
		cin >> a;

		i=0;
		do
		{
			tab[ i ]=a;
			i++;
			cout << "pozycja nr: " << i << " wynosi: " << a << endl;
			a -= 2;
		} while ( i < n );
		free( tab );
	}
	return 0;
}