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};
}
}
}
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());
}
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