LINQ joins

I will use two classes, to demonstrate my examples:

LINQ Joins

I will use two classes, to demonstrate my examples:

Var and IEnumerable with LINQ

 IEnumerable is an interface that can move forward only over a collection, it can’t move backward and between the items. Var is used to declare implicitly typed local variable means it tells the compiler to figure out the type of the variable at compilation time. A var variable must be initialized at the time of declaration. Both have its own importance to query data and data manipulation.

How to get the object with the largest value on one of its properties

Let’s assume we have a list of CampaignInfoData objects that have one property named NumberOfBatches of type int.

private List<CampaignInfoData> m_campaignInfosList = new List<CampaignInfoData>();

Find Dictionary duplicate values in C#

Here I use a simple LINQ statement to find duplicate values from dictionary.
 

Handling Nullable values in LINQ queries.

Suppose we have PhoneNum (nullable integer property) in Customer class
Public int PhoneNum {get;set;}

Check Null in lamda expression like below.

Public Ienumerable<Customer> GetCutomers(List<Customer> custList)
{
var query=custList.Where(c => (c.PhoneNum ?? false)== false);
}

 

LINQ “ThenBy” example.

Explain what the difference is between:

tmp = invoices.InvoiceCollection
              .OrderBy(sort1 => sort1.InvoiceOwner.LastName)
              .OrderBy(sort2 => sort2.InvoiceOwner.FirstName)
              .OrderBy(sort3 => sort3.InvoiceID); 

Generating sequence of Numbers using Linq.

Public Ienumerable BuildIntegerSequence()

{

var integers=Enumerable.Range(0,10); //0…9

var integers=Enumerable.Range(0,10).Select(i => 5+(10*i)); // 5,15,25…

return integers;

}

Select all items from one collection to another collection of same type

Public class xyz: ICloneable
{
// Properties

public object Clone()
{
return this.MemberwiseClone();
}
}

Null coalescing operator (??) example in C# and using it with LINQ & XML

The ?? operator can be very useful in these scenarios.