C++ แสดงเครื่องหมายจุลภาค

bool isabs(int p) //5
{
if (p<0)
return false;
return true;
}
int power(int p)
{
int sum = 1;
for (int i = 1; i <= p; i++)
{
sum *= 10;
}
return sum;
}
int main()
{
system("cls");
int n;
int m[30];
int is;
cout << "Enter Input : ";
cin >> n;
int a = abs(n);
is = isabs(n);
string s = to_string(a);
int k = s.length();
if (!is)
{
cout << "-";
}
else
cout << "";
for (int i = 0; i<k; i++)
{
m[i] = a % (power(k - i)) / (power(k - 1 - i));
}
for (int i = 0; i<k; i++)
{
if (i % (k - 1) == k - 4 || i % (k - 1) == k - 7)
{
cout << m[i]<< ",";
}
else
cout << m[i];
}
        retrun 0;
}