Number Of Times X Digit Occurs In Each And Every Number From 0 To N C++ code

#include <iostream>

using namespace std;

int count_3s(int n)
{
int counter = 0;
while (n > 0)
{
//for find number of digit
if (n % 10 == 3)
{
counter++;
}
// n/=10;
n = n / 10;
}
return counter;
}
int count_in_range(int n)
{
int counter = 0 ;
for (int i = 2; i <= n; i++)
{
counter = counter + count_3s(i);
}
return counter;
}
int main()
{ 
//initialize of n variables
int n;
cout<<"\nInsert the end value : ";
cin>>n;
cout<<"\nTotal occurrences of 3 from 0 to "<<n<<" is "<<count_in_range(n);
return 0;
}