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Queryable.SkipWhile<TSource> Method (IQueryable<TSource>, Expression<Func<TSource, Boolean>>)

Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements.

Namespace:  System.Linq
Assembly:  System.Core (in System.Core.dll)

public static IQueryable<TSource> SkipWhile<TSource>(
	this IQueryable<TSource> source,
	Expression<Func<TSource, bool>> predicate
)

Type Parameters

TSource

The type of the elements of source.

Parameters

source
Type: System.Linq.IQueryable<TSource>

An IQueryable<T> to return elements from.

predicate
Type: System.Linq.Expressions.Expression<Func<TSource, Boolean>>

A function to test each element for a condition.

Return Value

Type: System.Linq.IQueryable<TSource>
An IQueryable<T> that contains elements from source starting at the first element in the linear series that does not pass the test specified by predicate.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IQueryable<TSource>. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).

ExceptionCondition
ArgumentNullException

source or predicate is null.

This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T, TResult> types. For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

The SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource, Boolean>>) method generates a MethodCallExpression that represents calling SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource, Boolean>>) itself as a constructed generic method. It then passes the MethodCallExpression to the CreateQuery(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

The query behavior that occurs as a result of executing an expression tree that represents calling SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource, Boolean>>) depends on the implementation of the type of the source parameter. The expected behavior is that it applies predicate to each element in source until it finds an element for which predicate returns false. That element and all the remaining elements are returned.

The following code example demonstrates how to use SkipWhile<TSource>(IQueryable<TSource>, Expression<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 };

            // Get all grades less than 80 by first 
            // sorting the grades in descending order and then 
            // taking all the grades after the first grade 
            // that is less than 80.
            IEnumerable<int> lowerGrades =
                grades.AsQueryable()
                .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
            */

.NET Framework

Supported in: 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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