In .NET, at runtime: How to get the default value of a type from a Type object? [duplicate]

问题

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Closed 9 years ago.

Possible Duplicate:
Default value of a type

In C#, to get the default value of a Type, i can write...

var DefaultValue = default(bool);`

But, how to get the same default value for a supplied Type variable?.

public object GetDefaultValue(Type ObjectType)
{
    return Type.GetDefaultValue();  // This is what I need
}

Or, in other words, what is the implementation of the "default" keyword?

回答1:

I think that Frederik's function should in fact look like this:

public object GetDefaultValue(Type t)
{
    if (t.IsValueType)
    {
        return Activator.CreateInstance(t);
    }
    else
    {
        return null;
    }
}

回答2:

You should probably exclude the Nullable<T> case too, to reduce a few CPU cycles:

public object GetDefaultValue(Type t) {
    if (t.IsValueType && Nullable.GetUnderlyingType(t) == null) {
        return Activator.CreateInstance(t);
    } else {
        return null;
    }
}

来源：https://stackoverflow.com/questions/2686678/in-net-at-runtime-how-to-get-the-default-value-of-a-type-from-a-type-object