Find Substring and Reverse it in Windows Store App

Introduction

In this article I will explain how to find a substring from a string and if present then reverse the substring. Basically it is a frequently asked interview question. I have encountered this question many times in interviews. That is why I decided to write this article.

Now use the following procedure to implement it.

Step 1

First of all you have to create a new Windows Store Application, as in:

Open Visual Studio 2012
"File" -> "New" -> "Project..."
Choose "Template" -> "Visual C#" -> "Window Store app"
Choose "Blank App (XAML)" then rename the application

Step 2

Write the following XAML code in "Mainpage.Xaml" (that is available in Solution Explorer):

<Page

x:Class="number_app.MainPage"

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

xmlns:local="using:number_app"

xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"

mc:Ignorable="d">

<Grid.RowDefinitions>

</Grid.RowDefinitions>

<Grid.ColumnDefinitions>

</Grid.ColumnDefinitions>

</Grid>

</Page>

Step 3

Now write the following C# code for the button within "Mainpage.Xaml.cs".

using System;

using System.Collections.Generic;

using System.IO;

using System.Linq;

using Windows.Foundation;

using Windows.Foundation.Collections;

using Windows.UI.Xaml;

using Windows.UI.Xaml.Controls;

using Windows.UI.Xaml.Controls.Primitives;

using Windows.UI.Xaml.Data;

using Windows.UI.Xaml.Input;

using Windows.UI.Xaml.Media;

using Windows.UI.Xaml.Navigation;

using System.Text;

namespace number_app

{

public sealed partial class MainPage : Page

{

public MainPage()

{

this.InitializeComponent();

}

protected override void OnNavigatedTo(NavigationEventArgs e)

{

}

public void number(string str)

{

bool b= str.Contains(substr);

string temp = "";

if (b == true)

{

for (int i = substr.Length - 1; i >= 0; i--)

{

temp += substr[i];

}

str = str.Replace(substr, temp);

text1.Text = str;

}

else

{

text1.Text = "substring " + substr + " not found";

}

string str;

string substr;

private void button1_Click(object sender, RoutedEventArgs e)

{

str = null;

substr = null;

str = textbox1.Text;

substr = textbox2.Text;

number(str);

}

Step 4

Now Run your app.