entire code

#include <iostream>
#include<iomanip>
#include <cmath>
usingnamespace std;
int main()
{

char choice;
const int arraysize=20;
int num[arraysize];
do
{

cout<<"I will give you the Sum,Mean,Var & the Std Dev of any series of numbers?Y/N:"<<endl;
cin>>choice;
if(choice =='Y'||choice =='y')
{

cout<<"How many numbers will you enter? (up to 20)?"; cin>>num[arraysize];
for (int j=0;j<num[arraysize];j++)
{
cout<<"Enter Number"<<j+1<<":"; cin>> num[j];
}

cout << " You have entered the following:"<<endl;
for (j = 0; j < num[arraysize]; j++)
{

cout << num[j]<<" ";
}
int sum=0;
for (j=0;j<num[arraysize];j++)
sum+= num[j];
cout<<"\nThe Sum is "<<sum<<endl;

float mean= (sum/num[arraysize]);
cout << showpoint << fixed << setprecision (2);
cout<<"The Mean is "<<mean<<endl;
//not working

float var=((num[0]-mean)*pow(num[0]-mean,2) + (num[1]-mean)*pow(num[1]-mean,2) + + (num[2]-mean)*pow(num[2]-mean,2))/ (num[arraysize-1]);
cout << showpoint << fixed << setprecision (2);
cout<<"The Varience is " <<var<<endl;
//not working
float sqrtvar=sqrt(var);
cout << showpoint << fixed << setprecision (2);
cout<<"The Standard deviation is "<<sqrtvar<<endl;
//not working
}

}while(choice!='N'&& choice!='n');
return 0;

}