GetHashCode Method
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ValueType.GetHashCode Method ()


Returns the hash code for this instance.

Namespace:   System
Assembly:  mscorlib (in mscorlib.dll)

public override int GetHashCode()

Return Value

Type: System.Int32

A 32-bit signed integer that is the hash code for this instance.

The GetHashCode method applies to types derived from ValueType. One or more fields of the derived type is used to calculate the return value. If you call the derived type's GetHashCodemethod, the return value is not likely to be suitable for use as a key in a hash table. Additionally, if the value of one or more of those fields changes, the return value might become unsuitable for use as a key in a hash table. In either case, consider writing your own implementation of the GetHashCode method that more closely represents the concept of a hash code for the type.

For more information, see Object.GetHashCode, and System.Collections.Hashtable.

When you call the GetHashCode method on a Windows Runtime structure, it provides the default behavior for value types that don’t override GetHashCode. This is part of the support that the .NET Framework provides for the Windows Runtime (see .NET Framework Support for Windows Store Apps and Windows Runtime). Windows Runtime structures can’t override GetHashCode, even if they’re written with C# or Visual Basic, because they can’t have methods. (In addition, structures in the Windows Runtime itself don’t inherit ValueType.) However, they appear to have ToString, Equals, and GetHashCode methods when you use them in your C# or Visual Basic code, and the .NET Framework provides the default behavior for these methods.

The following example demonstrates how the GetHashCode method can be overridden by a derived value type.

public struct Complex 
	public double m_Re;
	public double m_Im;

	public override bool Equals( object ob ){
		if( ob is Complex ) {
			Complex c = (Complex) ob;
			return m_Re==c.m_Re && m_Im==c.m_Im;
		else {
			return false;

	public override int GetHashCode(){
		return m_Re.GetHashCode() ^ m_Im.GetHashCode();

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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