Is a double really unsuitable for money?

c# language-agnostic decimal currency
doekman picture doekman · Nov 25, 2008 · Viewed 17.3k times · Source

I always tell in c# a variable of type double is not suitable for money. All weird things could happen. But I can't seem to create an example to demonstrate some of these issues. Can anyone provide such an example?

(edit; this post was originally tagged C#; some replies refer to specific details of decimal, which therefore means System.Decimal).

(edit 2: I was specific asking for some c# code, so I don't think this is language agnostic only)

Answer

Marc Gravell picture Marc Gravell · Nov 25, 2008

Very, very unsuitable. Use decimal.

double x = 3.65, y = 0.05, z = 3.7;
Console.WriteLine((x + y) == z); // false

(example from Jon's page here - recommended reading ;-p)

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