automatic property with default value [duplicate]

This question already has answers here: 开发者_JS百科 Closed 10 years ago.

Possible Duplicate:

How do you give a C# Auto-Property a default value?

Is there any nice way to provide a default value for an automatic property?

public int HowHigh { get; set; } // defaults to 0

If not explicitly set anywhere, I want it to be 5. Do you know a simple way for it? E.g. I could set it in constructor or something, but that's not elegant.

UPDATE: C# 6 has got it: http://geekswithblogs.net/WinAZ/archive/2015/06/30/whatrsquos-new-in-c-6.0-auto-property-initializers.aspx

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No, there isn't any nice way of doing this - basically you have to set it in the constructor, which isn't pleasant.

There are various limitations to automatic properties like this - my biggest gripe is that there isn't a way to create a read-only automatic property which can be set in the constructor but nowhere else (and backed by a readonly field).

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Best you can do is set it in the constructor, you cannot make changes within automatic properties, you will need a backing field and implement the setter/getter yourself otherwise.

Using a backing field you can write something like this:

private int _howHigh = 0;
public int HowHigh { get {return _howHigh; }  set { _howHigh = value; } }

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If the default value for the type is not sufficient, then the only way to do it is via a constructor.

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In a word: No.

Automatic properties are a one trick pony, as soon as you need something extra (like a reasonable default value) you should revert to the backing field regular properties.

I'm a Resharper user, and it makes going from automatic to backed properties a breeze.

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The constructor is NOT the only option you have.

I believe this is best:

private int m_HowHigh = 5; 
public int HowHigh { 
    get { return m_HowHigh; }  
    set { m_HowHigh = value; } 
} 

I prefer this for readability purposes more than the ctor().

This is NOT what you want:

[DefaultValue(5)]
public int HowHigh { get; set; }

Reference: http://msdn.microsoft.com/en-us/library/system.componentmodel.defaultvalueattribute.aspx#Y2248

Because this is only a decoration and does not set the value (in C#4).