I having this error could anyone can help me :Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object at ValidParenthese.Solution.IsValid (System.String s) [0x00000] in <89120c6f256647e6a05011f274f6a

[swethamaddi]

using System;
using System.Collections.Generic;
using System.Linq;

namespace ValidParenthese {

public class Solution {
    public bool IsValid(string s) {
        var result = s.ToCharArray().ToList();
        bool value = true;

        for (int i = 0; i < result.Count; i++) {

            if (result\[i\].ToString().Equals("(")) {

                if (result\[i + 1\].ToString().Equals(")")) {
                    value = true;
                } else {
                    var count = result.Count;

                    if (count >= 3) {

                        var index = result\[i + 1\];

                        if (result\[i + 2\].ToString().Equals(")")) {
                            value = false;
                        } else if ((index.ToString().Equals("{") && result\[i + 2\].ToString().Equals("}"))
                            || (index.ToString().Equals("\[") && result\[i + 2\].ToString().Equals("\]"))) {

                            if (result\[i + 3\].ToString().Equals(")")) {
                                value = true;
                            } else {
                                var ind = result\[i + 2\];

                                if ((ind.ToString().Equals("{") && result\[i + 3\].ToString().Equals("}"))
                                    || (ind.ToString().Equals("\[") && result\[i + 3\].ToString().Equals("\]"))) {

                                    if ((index.ToString().Equals("{") && result\[i + 4\].ToString().Equals("}"))
                                        || (index.ToString().Equals("\[") && result\[i + 4\].ToString().Equals("\]"))) {
                                        if (result\[i + 5\].ToString().Equals(")")) {
                                            value = true;
                                        } else {
                                            value = false;
                                        }
                                    } else {
                                        value = false;
                                    }
                                } else {
                                    value = false;
                                }
                            }
                        }

                    } else {
                        value = false;
                    }


                }

            } else if (result\[

[Lost User]

See my answer to your original question on this subject.

[Dave Kreskowiak]

Hint: If you have to call .ToString more than twice in a single method, your design is showing signs of being flawed to the point of being unsalvageable and needs to be scrapped and your approach to the problem redesigned from scratch.

Asking questions is a skill CodeProject Forum Guidelines Google: C# How to debug code Seriously, go read these articles.
Dave Kreskowiak