我需要在我的ASP.NET MVC应用程序中显示的货币，但是，当货币是0，我想它来显示自由（局部当然！）代替$ 0.00元。

I need to display a currency in my ASP.NET MVC application but when the currency is 0 I would like it to display "Free" (localized of course!) instead of $0.00.

所以，当我有这样的事情......

So when I have something like this...

Decimal priceFree = 0.00;
Decimal priceNotFree = 100.00;

priceFree.ToString("C");
priceNotFree.ToString("C");

的输出是 $ 0.00 $ 100.00

The output is "$0.00" "$100.00"

我想它是 自由 $ 100.00

I would like it to be "Free" "$100.00"

我想我可以使用的ToString（字符串格式，的IFormatProvider formatProvider）方法来做到这一点，但我不知道如何去做。很明显我想重新使用尽可能多的NumberFormatInfo尽可能只有覆盖它当输入为0。在这种情况下，我可以简单的返回一个本地化的资源，包括我的免费的字符串。

I imagine I can use the .ToString(string format, IFormatProvider formatProvider) method to accomplish this but I'm not sure how to go about it. Obvious I want to reuse as much of the NumberFormatInfo as possible and only override it when the input is 0. In that case I can simple return a localized resource that contains my "Free" string.

那么，如何做到这一点？

So how do I do this?

感谢

推荐答案

我觉得去将是一个扩展方法最简单的方法：

I think the easiest way to go would be an extension method:

public static string ToPriceString(this decimal value) 
{
    if (value <= 0m) 
        return "Free"; // Your localized resource
    else 
        return value.ToString("C");
}

如果你想要去的的IFormatProvider 的上有MSDN 的一个很好的例子。

If you want to go with the IFormatProvider, there is a good example on MSDN.