AddArray

#include <iostream>
using namespace std;
int main(void)
{	int na;
	cin >> na;
	int *a = new int[na];
	cout << "array a" << endl;
	for(int i=0; i<na; i++)     {
        cin >> a[i];
	}

	int b[]={4,56,4,56,56,7,56,7,567};
	int nb = sizeof(b)/sizeof(int);
	cout << "array b" << endl;
	for(int i=0; i<nb; i++)     {
        cout << b[i] <<endl;
	}
	cout<<endl;

	int Old_na = na;
	na = na + nb;
	cout<<"old na\t"<<Old_na<<endl<<"nb\t"<<nb<<endl<<"new na\t"<<na<<endl<<endl;
	int j = 0;
	for(int i=Old_na; i<na; ++i)	{
		a[i] = b[j];
		++j;
	}
	
	cout<<"new array a"<<endl;
	for(int k=0; k<na; k++)	{
		cout<<a[k]<<endl;
	}
}

random

#include<iostream.h>
#include<time.h>
#include<stdlib.h>
int main(void)
{	
	int a[]={5,4,47,3,8,435,768,45,67};
	int n; 
	n = sizeof(a)/sizeof(int);	
	for(int i=0; i<n; i++)	{
		cout<<a[i]<<'\t';
	}
	cout<<endl;
	srand(static_cast<unsigned int>(time(0)));
	int ri = rand() % n;
	cout<<"random number is\t"<<a[ri]<<endl;
}