Reverse string logic without using reverse function

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Text;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void btnget_Click(object sender, EventArgs e)
    {
        lblreverse.Text = Reverse(txtInput.Text);
    }
    public static string Reverse(string inputString)
    {
        var chars = inputString.ToCharArray();
        for (int i = 0; i < (chars.Length / 2); i++)
        {
            var temp = chars[i];
            chars[i] = chars[chars.Length - 1 - i];
            chars[chars.Length - 1 - i] = temp;
        }
        return new string(chars);
    }

    public static string Reverse3(string inputString)
    {
        var result = new StringBuilder();
        for (int i = inputString.Length - 1; i >= 0; i--)
        {
            result.Append(inputString[i]);
        }
        return result.ToString();
    }

    public static string Reverse2(string inputString)
    {
        var result = new StringBuilder();
        foreach (char ch in inputString)
        {
            result.Insert(0, ch);
        }
        return result.ToString();
    }
}