I am here with another example, how to reverse words in a string or sentence?

I have tried with a approach. I would welcome other approaches, please share..

////// Complexity: O(n) + O(n)/2 ~ O(n)

public static string ReverseWordsInString(string str)
        {
            string reverse = ReverseString(str);
            string temp = "";
            foreach (string s in reverse.Split(' '))
            {
                temp += ReverseString(s) + ' ';
            }

            return temp;
        }

private static string ReverseString(string str)
        {
            char[] chars = str.ToCharArray();
            int j = str.Length-1;

            for (int i = 0; i<str.Length/2; i++)
            {
                char c = chars[i];
                chars[i] = chars[j];
                chars[j] = c;      
                j--;
            }
            return new string(chars);
        }

I am here with another example, how to reverse a string in different ways?

Below are the different ways to do it.

/// Need one extra array for result, need to traverse full array.

public static string ReverseString1 (string str)
        {
            char[] chars = str.ToCharArray();
            char[] result = new char[chars.Length];

            for (int i = 0, j = str.Length - 1; i < str.Length; i++, j--)
            {
                result[i] = chars[j];
            }

            return new string(result);
        }

-----------------------------------------------------------------

/// Uses swap method to reverse; need to traverse only half of the array.

public static string ReverseString2(string str)
        {
            char[] chars = str.ToCharArray();
            for (int i = 0, j = str.Length - 1; i < j; i++, j--)
            {
                char c = chars[i];
                chars[i] = chars[j];
                chars[j] = c;      
            }
            return new string(chars);
        }

------------------------------------------------------------------

/// Here is the use of in-place swap without any temp variable

public static string ReverseString3 (string str)
        {
            char[] chars = str.ToCharArray();
            for (int i = 0, j = str.Length - 1; i < j; i++, j--)
            {
                chars[i] = str[j];
                chars[j] = str[i];
            }
            return new string(chars);
        }

---------------------------------------------------------------------

/// String Reversal without Copy to Char Array it's i <= j as we need to get the middle character in case of odd number of characters in the string

public static string ReverseString3b(string str)
        {
            char[] chars = new char[str.Length];
            for (int i = 0, j = str.Length - 1; i <= j; i++, j--)
            {
                chars[i] = str[j];
                chars[j] = str[i];
            }
            return new string(chars);
        }

--------------------------------------------------------------------

 /// String reversal with stack [Please note here Stack_Array is my custom Stack class, you can replace this with provided by .NET]

public static string ReverseString4(string str)
        {
            Stack_Array stk1 = new Stack_Array(str.Length);
            foreach (char c in str)
                stk1.Push(c);
            string revString = null;
            foreach (char c in str)
                revString += stk1.Pop();
            return revString;
        }

-------------------------------------------------------------------

/// String reversal with XOR (^); interesting way to reversal
/// A [i] = A[i] ^ A[len] -> A[i]  = 80 ^ 73 -> A[i] = 25
/// A [len] = A[len] ^ A[i] -> A[len]  = 73 ^ 25 -> A[len] = 80
/// A [i] = A[i] ^ A[len] -> A[i]  = 25 ^ 80 -> A[i] = 73

public static string ReverseString5(string str)
        {
            char[] inputstream = str.ToCharArray();
            int length = str.Length - 1;
            for (int i = 0; i < length; i++, length--)
            {
                inputstream[i] ^= inputstream[length];
                inputstream[length] ^= inputstream[i];
                inputstream[i] ^= inputstream[length];
            }
            return new string(inputstream);
        }

-------------------------------------------------------------------

 /// Recursion method; simple and regular performance for small strings

public static string ReverseString_Rec(string str)
        {
            if (str.Length <= 1)
                return str;
            else
                return ReverseString_Rec(str.Substring(1)) + str[0];
        }

------------------------------------------------------------------

/// Another way of recursion; need to pass index as 0

public static string ReverseString_Rec2(string str, int index)
        {
            char[] chars = str.ToCharArray();
            int len = chars.Length;
            if (index < len / 2)
            {
                char c = chars[index];
                chars[index] = chars[len - index - 1];
                chars[len - index - 1] = c;
                index++;
                return ReverseString_Rec2(new string (chars), index);
            }
            else
            {
                return new string(chars);
            }
        }

Please let me know your comments/ suggestions or if you have better ways :)

This doesn't look difficult right :) however can u think of different ways to find first non-repeated character in a string?

I tried 3 different ways in C#. One with O(n^2) and 2 ways with O(n). Please suggest if you can think of better ways :)

 ///Complexity: O(n^2)

public static char FirstNonRepeatedCharInString (string str)
        {
            int i, j;
            bool isRepeted = false;

            char[] chars = str.ToCharArray();

            for (i=0; i<chars.Length;i++)
            {
                isRepeted = false;
                for (j=0;j<chars.Length;j++)
                {
                    if ((i!=j) && (chars[i]==chars[j]))
                    {
                        isRepeted = true;
                        break;
                    }
                }

                if (isRepeted ==false)
                {
                    return chars[i];
                }
            }
            return ' ';
        }

 ---------------------------------------------------------------------------------------------

 ///Complexity: O(n)

public static char FirstNonRepeatedCharInString2(string str)
        {
            Dictionary<char, int> l1 = new Dictionary<char, int>();
            int temp = 0;

            foreach (char c in str.ToCharArray())
            {
                if (l1.Keys.Contains(c))
                {
                    temp = l1[c];
                    l1[c] = temp + 1;
                    continue;
                }
                l1.Add(c,1);
            }

            if (l1.Values.Contains(1))
            {
                return l1.First(x => x.Value == 1).Key;
            }
            return ' ';
        }

----------------------------------------------------------------------------------------------

///Complexity: O(256) + O(n) + O(n) = O(n)

public static char FirstNonRepeatedCharInString3(string str)
        {
            int[] chars = new int[256];
            for (int i = 0; i < chars.Length; i++)
            {
                chars[i] = 0;
            }

            for (int i = 0; i < str.Length; i++)
            {
                chars[str[i]]++;
            }

            for (int i = 0; i < str.Length; i++)
            {
                if (chars[str[i]] == 1)
                {
                    return str[i];
                }
            }
            return ' ';
        }

Happy Programming!!

Let's discuss some of the amazing enhancements and new features of VS 2013 (RC) in general and mostly related to web technologies.

• VS IDE Changes:
• Feedback Icon
• Notification symbol
• Sign In option to save your profile
• Tools->Options is now searchable and resizable
•  Productivity Improvements:
• Enhanced Scroll Bar
• Auto Brace Completion
• Move the code by ALT + UP/Down Aero key
• Peek Definition
• ASP.NET Enhancements:
• Browsers Link (Bi-direction connection between VS and browser using Signal-R)
• Signal-R internally uses Web Sockets(HTML 5 API) when it's available of Injects through java script.
• Browsers Link Dashboard to manage tasks.
• Unused CSS can be identified using Snapshot CSS USES option in browser link
• Java Script Editor Changes:
• Methods lookup like C# Editor
• IntelliSense inside JavaScript for CSS/Html
• Enforce Coding Standard by JSHint (comes with Web Essentials, setting can be modified)
• HTML Editor Changes:
• IntelliSense Inside quotes.
• Auto HTML entities popup when type &
• Zen Coding supported using Web Essentials
• Move to HTML using ALT+1 and ALT+2 using Web Essentials
• Insert parent tags using ALT+SHIFT+W using Web Essentials
• Improved Smart tags to do regular tasks (e.g. Remove and Keep Children) uniformed across VS using CTRL + .
• Auto Formatting of tag when inserted in new line using Web Essentials (instead of CTRL+K, CTRL+D.
•  CSS Editor Changes:
• IntelliSense for CSS Ids inside file.
• IntelliSense for Class name inside file
• IntelliSense for html elements across project

I happened to encounter this trouble while trying to pass reference of a Property.

 public class LinkedListQ : QNode
 {

        private QNode head = null;

        public QNode Head
        {
            get
            {
                return head;
            }
        }

 class Program
 {
        static void Main(string[] args)
        {

             LinkedListQ que = new LinkedListQ();
             que.ReverseList(ref que.Head);   //Error "A property, indexer or dynamic member access may not be passed as an out or ref parameter"

        }

The reason as per MSDN is - Properties are not variables. They are methods, and cannot be passed to ref parameters.

The workaround I figured out is to change the head variable to internal in order to be accessible from Program class and pass head variable reference instead Property.

       internal QNode head = null;

       que.ReverseList(ref que.head);  //Works fine

Reference: https://msdn.microsoft.com/en-us/library/14akc2c7.aspx

• Database Engine Enhancement:
• In-Memory OLTP for ~10X performance gains by moving most used tables into memory.
• Updatable and clustered column store indexes for faster retrieval.
• Enhanced query processing for better performance without app changes.
• Buffer Pool extension to SSDs for faster paging.
• Resource Governor controls IO along with CPU and memory.
• Enhanced Always On now supports 8 secondary for better HA (High Availability)

• Business Intelligence Enhancement:
• Power Query (formally codename “Data Explorer”) in Excel makes easy to access Internal and External data (both Relational and Non-Relational).
• Power Map (formally codename “Geo Flow”) in Excel can be used to get insights with 3D visualization.
• Parallel Data Warehouse with Polybase to support querying Big Data with T-SQL.

• Cloud support Enhancement:
• Simplified cloud Backup and Deployment lets you Backup and Restore from SQL Azure/Windows Azure VM to SQL Server and vice-versa.
• HA/Always On in Azure helps to handle disaster recovery.

What's you most favorite feature :) let me know.. 

Reference: https://download.microsoft.com/download/8/4/F/84F00BE4-DAFE-4BA4-92AC-5D1080127984/SQL_Server_2014_CTP1_Product_Guide.zip

As we know that ASP.NET MVC by default takes following setting available in RouteConfig file (under App_Start folder).

 routes.MapRoute(
                name: "Default",
                url: "{controller}/{action}/{id}",
                defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
            );

This means when you run the application, Home controller will be invoked and it's Index method will be executed by taking parameter id (if any).

you can change this behavior, if it's making sense to you.

For example if you want to invoke Store controller and It's Browse method while loading the application, you just need to change few things (controller and action values) as below.

routes.MapRoute(
                name: "Default",
                url: "{controller}/{action}/{id}",
                defaults: new { controller = "Store", action = "Browse", id = UrlParameter.Optional }
            );

Optionally you may also change the id parameter but I would personally recommend not to change (to keep it generic) unless there is some unavoidable reason.

Look forward for your comments!!

While working on the requirement to fix the number of records per page in the report, I found that there is no such out of the box (OOB) property in SSRS 2012 to do so, However this can be achieved by some workarounds :). Below are the steps.

• Navigate to the Rows Groups section and then Details. Select Add Group -> Parent Group -> Choose Expression in Group By (Leave Add group header/Add group footer as unchecked)
• Paste the following code into the expression box.

=int((RowNumber(nothing)-1)/25)

• In the group property navigate to Page Breaks option and select "Between each instance of a group" and leave the other options below unchecked.
• If you run your report, you could get error saying "A sort expression for tablix ‘Tablix...’ uses the RowNumber function. RowNumber cannot be used in sort expressions."  To fix the error remove the default sorting expression created in the group properties.
• By default the added SSRS group also gets added in Tablix column, if you wish not to keep this, you can remove this (Be careful to delete columns only and not the columns and associated groups.

Since it's a workaround, it has some constraint too :) which is when you export the report to excel, it exports different pages into different sheets which may not acceptable in all the cases but if export to excel is not a requirement, you may live with it.

Please share your comments... 

Direct casting

Direct cast is most common way of casting one type to another, however it yields exception if casting can’t be done.

Below is the example to demonstrate the same.

object length = 3.2;

int test = (int)length; //Fails in runtime

Console.WriteLine(test);

is operator

is operator checks whether an object is compatible with a given type (on the right side) and the result of the evaluation is either true (if casting can be done) or false (if casting can’t be done) and since the result is always a Boolean value so there is no chance of runtime exception.

Below is the example to demonstrate the same.

object length = 3.2;

if (length is int) //Check if length can be cast to int

{

    Console.WriteLine(length);

}

as operator

The as operator is like a casting except that it yields null on conversion failure instead of raising an exception. So runtime exception can be avoided using null check.

Below is the example to demonstrate the same.

class MyClass //Sample class to test the scenario

 {

            int a;

            string b;

 }

 static void CastMe()        
 {       

            object name = new MyClass();

            string test = name as string;

            if (test != null) //Check if test is not null means i.e. casting can be done

            {               
                     Console.WriteLine(name);

            }

}

Look forward to see your comments... 

While working on WPF, I came to know some good Data grid tips and wanted to share you the same.

• Issue: WPF Data Grid is not reflecting the changed Item Source.

           Solution: If using MVVM pattern, Refresh the item source by below command.

           CollectionViewSource.GetDefaultView(<Your Data Grid collection name>).Refresh();

• Issue: How to open a context menu from data grid and assign event handler after clicking on menu item.

           Solution:

           Step A: create context menu by inserting the following code.

                       <Window.Resources>
                               <ContextMenu x:Key="mnuAddList" Name="mnuAddList">
                                     <MenuItem Name="mnuAdd" Header="Edit"  Command="{Binding PopUpAddCommand}">
                                     </MenuItem>
                                </ContextMenu>
                       </Window.Resources>

                       Please note that here Context menu key (i.e. mnuAddList) will be used to attach with data grid in the next step. Also PopUpAddCommand is a property (defined in View Model) of  DelegateCommand type which will have reference of event handler.

            Step B: Attach the menu created in step 1 with grid.

                       <DataGrid Name="grdAdd" ContextMenu ="{StaticResource mnuAddList}" >

• Issue: Visibility property is not setting for Grid column and by doing so getting error as "System.Windows.Data Error: 2 : Cannot find governing FrameworkElement or FrameworkContentElement for  target element. BindingExpression:Path=IsMyColumnVisibile; DataItem=null; target element is'DataGridTextColumn' (HashCode=7395880); target property is 'Visibility' (type'Visibility')" 

          Solution: DataGridColumns are not part of visual tree so they are not connected to the data context of the DataGrid due to that their visibility binding can't be done straight forward. To achieve this, following  steps needs to performed.

1. Add a proxy FrameworkElement in your ancestor panel's Resources.
2. Host it into an invisible ContentControl bound to its Content.
3. Use this ProxyElement as StaticResource for data context source in your visibility binding.

       Code snippet:

<StackPanel>
    <StackPanel.Resources>
       <BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" />
       <FrameworkElement x:Key="ProxyElement" DataContext="{Binding}"/>
    </StackPanel.Resources>
    <ContentControl Visibility="Collapsed" Content="{StaticResource ProxyElement}"/>
    <DataGrid AutoGenerateColumns="False">
        <DataGrid.Columns>
            <DataGridTextColumn Visibility="{Binding DataContext.IsMyColumnVisibile, Source={StaticResource ProxyElement}, Converter={StaticResource BooleanToVisibilityConverter}}" Binding="{Binding MyColumn}"/>
        </DataGrid.Columns>
    </DataGrid>
</StackPanel> 

Appreciate your comments!