Get sum of dinamicaly changed array without LINQ and array.resize

iJunior_C#_Lesson_40

using System;

namespace iJuniorPractice
{
    class Program
    {
        static void Main(string[] args)
        {
            const string SumCommand = "sum";
            const string ExitCommand = "exit";
            
            int sum = 0;
            int arrayLength = 0;
            int[] numbers = new int[arrayLength];
            string input;
            bool isWork = true;

            while (isWork)
            {
                Console.Write($"Enter a number to add to the array, or type {SumCommand} to calculate the sum, or {ExitCommand} to quit: ");
                input = Console.ReadLine();
                
                switch (input)
                {
                    case SumCommand:
                        foreach (var number in numbers)
                        {
                            sum += number;
                        }

                        Console.WriteLine($"Sum of the array elements: {sum}");
                        break;

                    case ExitCommand:
                        Console.WriteLine("Exiting the program.");
                        isWork = false;
                        break;
                    
                    default:
                        int enteredNumber;
                        
                        while (int.TryParse(input, out enteredNumber) == false)
                        {
                            Console.WriteLine("Invalid input. Please enter an integer.");
                            input = Console.ReadLine();
                        }
                        
                        arrayLength++;
                        int[] temporary = new int[arrayLength];

                        for (int i = 0; i < numbers.Length; i++)
                        {
                            temporary[i] = numbers[i];
                        }

                        temporary[arrayLength - 1] = enteredNumber;
                        numbers = temporary;
                        Console.WriteLine("Number added to the array.");
                        break;
                }
            }
        }
    }
}