the C++ code to convert from base 16 to base 10:

 Here is the C++ code to convert from base 16 to base 10:

#include 
using namespace std;

int main() {
  string hex_number;
  cout << "Enter a hexadecimal number: ";
  cin >> hex_number;

  int decimal_number = 0;
  for (int i = 0; i < hex_number.length(); i++) {
    int digit = hex_number[i] - '0';
    if (digit > 9) {
      digit = hex_number[i] - 'A' + 10;
    }
    decimal_number = decimal_number * 16 + digit;
  }

  cout << "The decimal equivalent of " << hex_number << " is " << decimal_number << endl;

  return 0;
}