c++ access denied

#include <iostream>
#include <string>
using namespace std;

int ret, retu;
string pass_in, user_in;
string user = "Simon";
string pass = "test";

int checkLogin(string user_inn, string pass_inn) {
  if(user_in == "" || pass_in == "") {
             ret = 2;
  }
  else {
             if(user_inn == user && pass_inn == pass) {
                        ret = 0;
             }
             else {
                        ret = 1;
             }
  }
  return ret;
}

int main ()
{
  cout << "Username: ";
  getline (cin, user_in);
  cout << "Password: ";
  getline (cin, pass_in);
  ret = checkLogin(user_in, pass_in);
  switch(ret) {
              case 0:
                   cout << "Access Denied.\n";
                   break;
              case 1:
                   cout << "Access Denied.\n";
                   break;
              case 2:
                   cout << "Fill in all fields";
                   break;
              default:
                   cout << "Access Denied.\n";
                   break;
  }
  cin.get();
}

#include <iostream>
#include <string>
using namespace std;
 
int ret, retu;
string pass_in, user_in;
string user = "Simon";
string pass = "test";
 
int checkLogin(string user_inn, string pass_inn) {
  if(user_in == "" || pass_in == "") {
             ret = 2;
  }
  else {
             if(user_inn == user && pass_inn == pass) {
                        ret = 0;
             }
             else {
                        ret = 1;
             }
  }
  return ret;
}
 
int main ()
{
  cout << "Username: ";
  getline (cin, user_in);
  cout << "Password: ";
  getline (cin, pass_in);
  ret = checkLogin(user_in, pass_in);
  switch(ret) {
              case 0:
                   cout << "Access Denied.\n";
                   break;
              case 1:
                   cout << "Access Denied.\n";
                   break;
              case 2:
                   cout << "Fill in all fields";
                   break;
              default:
                   cout << "Access Denied.\n";
                   break;
  }
  cin.get();
}

string stringnaam

string stringnaam

char *stringnaam

char *stringnaam

if(user_inn == user && pass_inn == pass) {

if(user_inn == user && pass_inn == pass) {

if(user_inn == "user" && pass_inn == "pass") {

if(user_inn == "user" && pass_inn == "pass") {