ToArray ToDictionary ToList ToLookup ToSequence DefaultIfEmpty ElementAt in Visual Basic .NET

Painting QR Code 2d barcode in Visual Basic .NET ToArray ToDictionary ToList ToLookup ToSequence DefaultIfEmpty ElementAt

Operation ---

Description Returns the last element in a sequence Similar to Last but also returns a default element when the last element in the sequence is not available Returns a sequence s single element that satisfies a condition specified as an argument Similar to Single but also returns a default value when the single element is not found in the sequence Checks whether two sequences are equal Returns an empty sequence for the specified data type Generates a numeric sequence from a range of two numbers Generates a sequence by repeating the provided element a specified number of times Groups the elements of a sequence Performs a grouped join of two sequences based on matching keys Performs an inner join of two sequences based on matching keys

(Continued)

Equality Generation ---

Description Orders the elements of the sequence according to one or more keys Similar to OrderBy but sorts the sequence inversely Reverses the elements of the sequence Useful for specifying additional ordering keys after the first one specified by either the OrderBy or OrderByDescending operator Similar to ThenBy but sorts the sequence inversely Skips a given number of elements from a sequence and then yields the remainder of the sequence Similar to Skip but the numbers of elements to skip are defined by a Boolean condition Takes a given number of elements from a sequence and skips the remainder of the sequence Similar to Take but the numbers of elements to take are defined by a Boolean condition Defines the elements to pick in a sequence Performs a one-to-manyelements projection over a sequence

----

Projection --

Description Checks all the elements of a sequence against the provided condition Checks whether any element of the sequence satisfies the provided condition Checks for an element s presence into a sequence Filters a sequence based on the provided condition Returns distinct elements from a sequence Produces a sequence that is the difference between elements of two sequences Produces a sequence resulting from the common elements of two sequences Produces a sequence that is the union of two sequences

-Restriction Set --

In the rest of this chapter we ll examine each operator carefully, and consider examples that illustrate the elements functionality. The examples will be based on numeric sequences for operators that use numbers, and on classes such as Person, Role, and Salary for operators that use more-complex sequences. Listing 1-10 shows these classes.

Public Class Person Dim _id As Integer Dim _idRole As Integer Dim _lastName As String Dim _firstName As String Public Property ID() As Integer

Get Return _id End Get Set(ByVal value As Integer) _id = value End Set End Property Public Property IDRole() As Integer Get Return _idRole End Get Set(ByVal value As Integer) _idRole = value End Set End Property Public Property LastName() As String Get Return _lastName End Get Set(ByVal value As String) _lastName = value End Set End Property Public Property FirstName() As String Get Return _firstName End Get Set(ByVal value As String) _firstName = value End Set End Property End Class Public Class Role Dim _id As Integer Dim _roleDescription As String Public Property ID() As Integer Get

Return _id End Get Set(ByVal value As Integer) _id = value End Set End Property Public Property RoleDescription() As String Get Return _roleDescription End Get Set(ByVal value As String) _roleDescription = value End Set End Property End Class Public Class Salary Dim _idPerson As Integer Dim _year As Integer Dim _salary As Double Public Property IDPerson() As Integer Get Return _idPerson End Get Set(ByVal value As Integer) _idPerson = value End Set End Property Public Property Year() As Integer Get Return _year End Get Set(ByVal value As Integer) _year = value End Set End Property Public Property SalaryYear() As Double Get