Enumerable.SkipWhile Method
Definition
Important
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Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements.
Overloads
| SkipWhile<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) |
Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements. |
| SkipWhile<TSource>(IEnumerable<TSource>, Func<TSource,Int32,Boolean>) |
Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements. The element's index is used in the logic of the predicate function. |
SkipWhile<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)
- Source:
- Skip.cs
- Source:
- Skip.cs
- Source:
- Skip.cs
Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements.
public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static System::Collections::Generic::IEnumerable<TSource> ^ SkipWhile(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, bool> ^ predicate);public static System.Collections.Generic.IEnumerable<TSource> SkipWhile<TSource> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,bool> predicate);static member SkipWhile : seq<'Source> * Func<'Source, bool> -> seq<'Source><Extension()>
Public Function SkipWhile(Of TSource) (source As IEnumerable(Of TSource), predicate As Func(Of TSource, Boolean)) As IEnumerable(Of TSource)Type Parameters
- TSource
The type of the elements of source.
Parameters
- source
- IEnumerable<TSource>
An IEnumerable<T> to return elements from.
Returns
An IEnumerable<T> that contains the elements from the input sequence starting at the first element in the linear series that does not pass the test specified by predicate.
Exceptions
source or predicate is null.
Examples
The following code example demonstrates how to use SkipWhile<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) to skip elements of an array as long as a condition is true.
int[] grades = { 59, 82, 70, 56, 92, 98, 85 };
IEnumerable<int> lowerGrades =
grades
.OrderByDescending(grade => grade)
.SkipWhile(grade => grade >= 80);
Console.WriteLine("All grades below 80:");
foreach (int grade in lowerGrades)
{
Console.WriteLine(grade);
}
/*
This code produces the following output:
All grades below 80:
70
59
56
*/
' Create an array of integers that represent grades.
Dim grades() As Integer = {59, 82, 70, 56, 92, 98, 85}
' Sort the grades in descending order and
' get all grades greater less than 80.
Dim lowerGrades As IEnumerable(Of Integer) =
grades _
.OrderByDescending(Function(grade) grade) _
.SkipWhile(Function(grade) grade >= 80)
' Display the results.
Dim output As New System.Text.StringBuilder("All grades below 80:" & vbCrLf)
For Each grade As Integer In lowerGrades
output.AppendLine(grade)
Next
Console.WriteLine(output.ToString())
' This code produces the following output:
'
' All grades below 80:
' 70
' 59
' 56
Remarks
The SkipWhile<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) method is implemented by using deferred execution. The immediate return value is an object that stores all the information that is required to perform the action. The query represented by this method is not executed until the object is enumerated either by calling its GetEnumerator method directly or by using foreach in C# or For Each in Visual Basic.
This method tests each element of source by using predicate and skips the element if the result is true. After the predicate function returns false for an element, that element and the remaining elements in source are yielded and there are no more invocations of predicate.
If predicate returns true for all elements in the sequence, an empty IEnumerable<T> is returned.
The TakeWhile and SkipWhile methods are functional complements. Given a collection sequence coll and a pure function p, concatenating the results of coll.TakeWhile(p) and coll.SkipWhile(p) yields the same sequence as coll.
In Visual Basic query expression syntax, a Skip While clause translates to an invocation of SkipWhile.
See also
Applies to
SkipWhile<TSource>(IEnumerable<TSource>, Func<TSource,Int32,Boolean>)
- Source:
- Skip.cs
- Source:
- Skip.cs
- Source:
- Skip.cs
Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements. The element's index is used in the logic of the predicate function.
public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static System::Collections::Generic::IEnumerable<TSource> ^ SkipWhile(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, int, bool> ^ predicate);public static System.Collections.Generic.IEnumerable<TSource> SkipWhile<TSource> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,int,bool> predicate);static member SkipWhile : seq<'Source> * Func<'Source, int, bool> -> seq<'Source><Extension()>
Public Function SkipWhile(Of TSource) (source As IEnumerable(Of TSource), predicate As Func(Of TSource, Integer, Boolean)) As IEnumerable(Of TSource)Type Parameters
- TSource
The type of the elements of source.
Parameters
- source
- IEnumerable<TSource>
An IEnumerable<T> to return elements from.
A function to test each source element for a condition; the second parameter of the function represents the index of the source element.
Returns
An IEnumerable<T> that contains the elements from the input sequence starting at the first element in the linear series that does not pass the test specified by predicate.
Exceptions
source or predicate is null.
Examples
The following code example demonstrates how to use SkipWhile<TSource>(IEnumerable<TSource>, Func<TSource,Int32,Boolean>) to skip elements of an array as long as a condition that depends on the element's index is true.
int[] amounts = { 5000, 2500, 9000, 8000,
6500, 4000, 1500, 5500 };
IEnumerable<int> query =
amounts.SkipWhile((amount, index) => amount > index * 1000);
foreach (int amount in query)
{
Console.WriteLine(amount);
}
/*
This code produces the following output:
4000
1500
5500
*/
' Create an array of integers.
Dim amounts() As Integer =
{5000, 2500, 9000, 8000, 6500, 4000, 1500, 5500}
' Skip items in the array whose value is greater than
' the item's index times 1000; get the remaining items.
Dim query As IEnumerable(Of Integer) =
amounts.SkipWhile(Function(amount, index) _
amount > index * 1000)
' Output the results.
Dim output As New System.Text.StringBuilder
For Each amount As Integer In query
output.AppendLine(amount)
Next
Console.WriteLine(output.ToString())
' This code produces the following output:
'
' 4000
' 1500
' 5500
Remarks
This method is implemented by using deferred execution. The immediate return value is an object that stores all the information that is required to perform the action. The query represented by this method is not executed until the object is enumerated either by calling its GetEnumerator method directly or by using foreach in C# or For Each in Visual Basic.
The SkipWhile<TSource>(IEnumerable<TSource>, Func<TSource,Int32,Boolean>) method tests each element of source by using predicate and skips the element if the result is true. After the predicate function returns false for an element, that element and the remaining elements in source are yielded and there are no more invocations of predicate.
If predicate returns true for all elements in the sequence, an empty IEnumerable<T> is returned.
The first argument of predicate represents the element to test. The second argument represents the zero-based index of the element within source.
The TakeWhile and SkipWhile methods are functional complements. Given a collection sequence coll and a pure function p, concatenating the results of coll.TakeWhile(p) and coll.SkipWhile(p) yields the same sequence as coll.
In Visual Basic query expression syntax, a Skip While clause translates to an invocation of SkipWhile.
