Code 2 - Driving

#include<iostream>
#include<stdlib.h>
#include<time.h>
using namespace std;

void writeMenu(){
    cout<<"1. Start driving"<<endl;
    cout<<"2. Rest"<<endl;
    cout<<"3. Exit"<<endl;
}

void hold(){
    cin.clear();
    cin.ignore();
    getchar();
}

int gasoline = 100;
int input, speed, doneRandom = 0;

int main(){

    system("cls");

    cout<<"Your gasoline's car: "<<gasoline<<" liters"<<endl;
    cout<<"========================"<<endl;
    writeMenu();
    cin>>input;
    if(!cin){
        cin.clear();
        cin.ignore();
        main();
    } else {
        switch(input){
            case 1:

                /* initialize random seed: */
                srand (time(NULL));

                /* generate secret number between 1 and 10: */
                if(doneRandom == 0){
                    speed = rand() % 100 + 1;
                    doneRandom = 1;
                }
                cout<<"Your speed : "<<speed<<" km/hour"<<endl;
                if(speed >= 50){
                    if(gasoline >= 40){
                        gasoline -= 40;
                        cout<<"You have spent 40 liters gasoline"<<endl;
                    } else {
                        cout<<"Your gasoline is not enough to run the car..."<<endl;
                    }
                } else {
                    if(gasoline >= 20){
                        gasoline -= 20;
                        cout<<"You have spent 20 liters gasoline"<<endl;
                    } else {
                        cout<<"Your gasoline is not enough to run the car..."<<endl;
                    }
                }
                hold();
                main();
                break;
            case 2:

                if(gasoline == 100){
                    cout<<"Your gasoline is full"<<endl;
                } else {
                    if(gasoline > 80){
                        gasoline = 100;
                        cout << "Your gasoline is now fully recharged" << endl;
                    } else {
                        gasoline += 20;
                        cout << "Successfully recharged 20 liters gasoline" << endl;
                    }
                }
                hold();
                main();
                break;
            case 3:

                cout<<"Thank you..."<<endl;
                exit(0);
                break;

            default:
                cout<<"inputan salah"<<endl;
                cin.clear();
                cin.ignore();
                break;
        }
    }

}