C# Bills Management

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace College_Classes
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] billsNames = new string[0];
            int[] billsPayments = new int[0];
            int option = 0;
            do
            {
                Console.WriteLine("1. Print Bills\n2. Add Bill\n3. Get bill payment by bill name\n4. Average payment\n5. Print max bill payment\n6. Remove Bill\n7. Exit");
                option = int.Parse(Console.ReadLine());
                if(option >= 1 && option <= 7 && option != 2 && option != 7 && billsNames.Length == 0)
                {
                    Console.WriteLine("You don't have any bills");
                    Console.ReadKey();
                    Console.Clear();
                    continue;
                }
                if(option == 1) // Print Bills
                {
                    PrintBills(billsNames, billsPayments);
                }
                else if (option == 2) // Add Bill
                {
                    billsNames = ModifiedStringArray(billsNames, 1);
                    billsPayments = ModifiedIntegerArray(billsPayments, 1);
                    Console.Write("Please enter a new bill name: ");
                    billsNames[billsNames.Length - 1] = Console.ReadLine();
                    Console.Write($"Please enter {billsNames[billsNames.Length -1]}'(s) payment: ");
                    billsPayments[billsPayments.Length - 1] = int.Parse(Console.ReadLine());
                    PrintBills(billsNames, billsPayments);
                }
                else if (option == 3) // Find Bill by Name
                {
                    Console.Write("Please enter the bill's name: ");
                    string tmpstr = Console.ReadLine();
                    bool found = false;
                    for (int i = 0; i < billsNames.Length; i++)
                    {
                        if (tmpstr == billsNames[i])
                        {
                            PrintBills(billsNames, billsPayments, i);
                            found = true;
                        }
                    }
                    if (found == false) Console.WriteLine($"The bill \"{tmpstr}\" was not found!");
                }
                else if (option == 4) // Average Bill Payment
                {
                    double sum = 0;
                    for (int i = 0; i < billsPayments.Length; i++)
                    {
                        sum += billsPayments[i];
                    }
                    sum /= billsPayments.Length;
                    Console.WriteLine($"Average bill payment: {sum}");
                }
                else if (option == 5) // Maximum Value Bill
                {
                    int max = 0, maxSlot = 0;
                    for (int i  = 0; i < billsPayments.Length; i++)
                    {
                        if(billsPayments[i] > max)
                        {
                            max = billsPayments[i];
                            maxSlot = i;
                        }
                    }
                    Console.WriteLine($"Max bill: {billsNames[maxSlot]} (${billsPayments[maxSlot]})");
                }
                else if (option == 6) // Delete Bill
                {
                    Console.Write("Please enter the name of the bill you'd like to delete: ");
                    string tmpstr = Console.ReadLine();
                    bool found = false;
                    for (int i = 0; i < billsNames.Length; i++)
                    {
                        if (tmpstr == billsNames[i])
                        {
                            Console.WriteLine($"The bill \"{billsNames[i]}\" (${billsPayments[i]}) has been deleted!");
                            billsNames[i] = "";
                            billsPayments[i] = 0;
                            billsNames = ModifiedStringArray(billsNames, -1);
                            billsPayments = ModifiedIntegerArray(billsPayments, -1);
                            found = true;
                        }
                    }
                    if (found == false) Console.WriteLine($"The bill \"{tmpstr}\" was not found!");
                }
                else if (option == 7) // Exit
                {
                    Console.WriteLine("Exiting...");
                }
                else Console.WriteLine("Stop cuasing troubles, pick 1 to 7.");
                Console.ReadKey();
                Console.Clear();
            }
            while (option != 7);
        }

        static void PrintBills(string[] bNames, int[] bPayments, int slotid = -1)
        {
            if (slotid != -1) Console.WriteLine($"Bill Name: {bNames[slotid]}, Amount: {bPayments[slotid]}");
            else for(int i = 0; i < bNames.Length; i++) Console.WriteLine($"Bill Name: {bNames[i]}, Amount: {bPayments[i]}");
        }

        static string[] ModifiedStringArray(string[] array, int size)
        {
            string[] tmpstr = new string[array.Length + size];
            int emptyCount = 0;
            for (int i = 0; i < array.Length; i++)
            {
                if (array[i] == "")
                {
                    emptyCount++;
                    continue;
                }
                tmpstr[i-emptyCount] = array[i];
            }
            return tmpstr;
        }

        static int[] ModifiedIntegerArray(int[] array, int size)
        {
            int[] tmpint = new int[array.Length + size];
            int emptyCount = 0;
            for (int i = 0; i < array.Length; i++)
            {
                if(array[i] == 0)
                {
                    emptyCount++;
                    continue;
                }
                tmpint[i-emptyCount] = array[i];
            }
            return tmpint;
        }

    }
}