How to initialise dynamic integer array with 0 when using new pointer in C++?

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C++

#include<iostream>
using namespace std;
class peak
{
    int n,*p,*q;
public:
    void get()
    {
        cout<<"\nenter how many elements u want in array";
        cin>>n;
    }
    void create()
    {
        p=new int[n];
        q=new int[n];
    }
    void find();
    void show();
    void input();
    void del()
    {
        delete []p;
        delete []q;
    }
};
void peak:: find()
    {
        int j=0,i=1;
        if(p[0]>p[1])
            q[j++]=p[0];
        for(i=1;i<n-1;i++)
        {
            if(p[i]>p[i-1] && p[i]>p[i+1])
                q[j++]=p[i];
        }
        if(p[i]>p[i-1])
            q[j]=p[i];
    }
    void peak::show()
    {
        cout<<"\nthe peak elements are:";
        for(int i=0;i<n;i++)
            //showing different garbage for *(q+i):6750404 and q[i]:3080388
            cout<<q[i]<<"\t";
    }
    void peak::input()
    {
        cout<<"\nenter elements ";
        for(int i=0;i<n;i++)
            cin>>p[i];
    }
    int main()
    {
        peak p;
        p.get();
        p.create();
        p.input();
        p.find();
        p.show();
        p.del();
        return 0;
    }

What I have tried:

the expression:
p=new int[n](0) doesn't works as is during dynamic allocation of single integer as:p=new int(25);
also,output of above program for n=4 and entries:5 10 20 15 is:
20 garbage 0 0
required output:20 0 0 0
for the same code,if n=7 with entries:10 20 15 2 23 90 67 is:
20 90 0 0 0 0 0 which is the required output without any garbage!
why so?kindly help.