Question with floating point addition
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19-09-2019 - |
Question
float totalAmount = 0;
.
.
.//totalAmount assigned value 1.05 correctly
.
totalAmount += float.Parse(dataRow["Amt"].ToString()); //where dataRow["Amt"] has value 4.93
The answer I get for totalAmount is 5.97999954 instead of 5.98
Why is this happening?
Solution
You state that totalAmount
is 1.05, before the accumulation. That would give expected results of:
1.05
4.93 +
------
5.98
You are getting 5.97999954, which is basically the answer as best represented by IEEE floating point, which is a binary format that cannot exactly express every decimal number. For instance, the rather common 0.110 has an infinite binary floating point representation .0001100110011...
2.
And a Wikipedia link, for good measure: http://en.wikipedia.org/wiki/Floating_point#Accuracy_problems ;)
OTHER TIPS
jdmichal is correct, but I'll add that, if you actually want this to add up correctly, you could use the Decimal type (including decimal literals).