System.StringComparer Class

Represents a string comparison operation that uses specific case and culture-based or ordinal comparison rules.

See Also: StringComparer Members


public abstract class StringComparer : IComparer<string>, IEqualityComparer<string>, IComparer, IEqualityComparer


An object derived from the StringComparer class embodies string-based comparison, equality, and hash code operations that take into account both case and culture-specific comparison rules. You can use the StringComparer class to create a type-specific comparison to sort the elements in a generic collection. Classes such as Hashtable, Dictionary`2, SortedList, and SortedList`2 use the StringComparer class for sorting purposes.

A comparison operation that is represented by the StringComparer class is defined to be either case-sensitive or case-insensitive, and use either word (culture-sensitive) or ordinal (culture-insensitive) comparison rules. For more information about word and ordinal comparison rules, see System.Globalization.CompareOptions.

Implemented Properties

You might be confused about how to use the StringComparer class properties because of a seeming contradiction. The StringComparer class is declared abstract (MustInherit in Visual Basic), which means its members can be invoked only on an object of a class derived from the StringComparer class. The contradiction is that each property of the StringComparer class is declared static (Shared in Visual Basic), which means the property can be invoked without first creating a derived class.

You can call a StringComparer property directly because each property actually returns an instance of an anonymous class that is derived from the StringComparer class. Consequently, the type of each property value is StringComparer, which is the base class of the anonymous class, not the type of the anonymous class itself. Each StringComparer class property returns a StringComparer object that supports predefined case and comparison rules.


Namespace: System
Assembly: mscorlib (in mscorlib.dll)
Assembly Versions:,
Since: .NET 2.0