Writing a smart contract in C++

#include <iostream>
#include <cstdlib>
#include <cstring>

using namespace std;

// Copied from C version
static int envAtoi(const char* env) {
  const char* val = getenv(env);
  if (val == NULL) {
    return 0;
  }
  return atoi(val);
}

int maxUser = 100;

static void construct() {
  const char* val = getenv("DB_QVM_INITIALIZED");
  if (val && strcmp(val, "true") == 0) {
    cerr << "contract is already initialized" << endl;
    exit(1);
  }
  cout << "DBW=QVM_INIT_MAXUSER=" << maxUser << endl;
}

static void initialize() {
  const char* val = getenv("DB_QVM_INITIALIZED");
  if (val == NULL || strcmp(val, "true") != 0) {
    cerr << "contract is already not initialized" << endl;
    exit(1);
  }
  maxUser = envAtoi("DB_QVM_INIT_MAXUSER");
}

int main(int argc, char *argv[]) {
  if (argc == 2 && strcmp(argv[1], "construct") == 0) {
    construct();
    exit(0);
  }
  // THIS SAMPLE ONLY SUPPORTS THE "register" FUNCTION
  if (argc == 3 && strcmp(argv[1], "register") == 0) {
    initialize();
    // GET THE CURRENT USER'S NAME
    const char *previousName = getenv("DB_USER_CURRENT");
    // OR DEFAULT TO "unknown" IF THIS IS THE FIRST CALL
    if (previousName == NULL || strlen(previousName) == 0) {
      previousName = "unknown";
    }
    // GET THE TOTAL USER COUNT
    int totalUserCount = envAtoi("DB_TOTALUSERS");
    // WRITE PREVIOUS USER NAME TO STDOUT
    cout << "OUT=prevname: " << previousName << endl;
    // UPDATE CURRENT USER NAME BY WRITING IT TO DB
    cout << "DBW=USER_CURRENT=" << argv[2] << endl;
    // STORE USER NAME UNDER A STORAGE SLOT FOR PERSISTENCE (CURRENT GETS OVERWRITTEN ON EACH CALL)
    cout << "DBW=USER_" << totalUserCount << "=" << argv[2] << endl;
    // INCREMENT THE TOTAL USER COUNT
    cout << "DBW=TOTALUSERS=" << totalUserCount+1 << endl;
    return 0;
  }
  if (argc >= 2) {
    cerr << "Wrong CMD: " << argv[1] << endl;
    exit(1);
  }
  cerr << "Wrong args!" << endl;
  exit(1);
}