Exception says stack is empty when it is not?

I am learning about some advanced collections etc in my book, and have come across stacks. I get the concept but wanted to make a quick program that removes an item from a defined point in the stack then places all the values back onto the stack. I have my code here but I am getting an exception of type System.InvalidOperationException, with additional info of the stack being empty. I can't seem to get why; can anyone help?

Here is my code:

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

namespace StackRemover
{
    class Program
    {
        static void Main(string[] args)
        {
            int index = 0; //the index they want to remove
            Stack[] array = new Stack[1]; // will hold the array returned by remove()
            Stack stack = new Stack();

            //fill the stack with values from 0 to 100
            for (int y = 0; y != 100; y++ )
            {
                stack.Push(y);
            }

            //print all items from stack
            foreach (var item in stack) 
            {
                Console.WriteLine(item.ToString());
            }

            Console.WriteLine("\n\nEnter an index to remove: ");
            index = Convert.ToInt32(Console.ReadLine());
            array = remover(stack, index);

            Console.WriteLine("\n\n" + array[1].Pop().ToString() + "\n\n"); //print the value of the removed index

            //print the rest of the values
            foreach(var item in array[0])
            {
                Console.WriteLine(item.ToString());
            }
        }

        public static Stack[] remover(Stack stack, int index)
        {
            Stack holding_stack = new Stack(); // used for holding values temporarily
            Stack value_stack = new Stack();   // will be returned with the desired index only
            int stack_length = stack.Count;
            int target = index - 1; // the index before the one we want to remove
            int current_index = 0;

            //if the index is larger than the stack size
            if(index > stack_length)
            {
                throw new Exception("Index bigger than stack!");
            }

            //pop items from stack and place them onto a temporary stack until we reach target
            while(current_index != target)
            {
                holding_stack.Push(stack.Pop()); //ERROR OCCURS HERE, System.InvalidOperationException, says that the stack is empty?
            }

            value_stack.Push(stack.Pop()); // push the index we were passed onto our third stack

            //place all the values from the holding stack back onto the passed stack
            while(holding_stack.Count != 0)
            {
                stack.Push(holding_stack.Pop());
            }

            return new Stack[]{stack, value_stack};

        }
    }
}
Jon Skeet
people
quotationmark

Look at your loop:

while(current_index != target)
{
    holding_stack.Push(stack.Pop());
}

How do you expect that loop to ever finish? You don't change either target or current_index in the body of the loop... Perhaps you meant to increase current_index in the loop? If so, might I suggest that a for loop would be simpler than a while loop?

As a side note, it's worth following .NET naming conventions - where methods are PascalCased and variables are camelCased, with no underscores.

So you might end up with:

for (int i = 0; i < target; i++)
{
    holdingStack.Push(stack.Pop());
}

people

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