CODEWITHSUNDEEP
c#doubletype-conversion
fhnaseer
fhnaseer

Reputation: 7267

Converting double to float in C# giving wrong values

Question is real simple. I have a double which I want to convert to float.

double doubleValue = 0.00000000000000011102230246251565;
float floatValue = (float)doubleValue;

Now when I do this. Float value just goes mad. Its value is "1.110223E-16" Do I need to do something extra for this flow. Value should be 0 or 0.1 but it is not here. What the problem here?

Upvotes: 3

Views: 3484

Answers (5)

Soner Gönül
Soner Gönül

Reputation: 98740

Double is double-precision floating-point number but float is single-precision floating-point number.

So normally, you can loss precision when you convert Double to float. 1.110223E-16 is equal something like 0.0000000000000001110223 as it representation.

If you want to round the nearest number your values, you can use Math.Round() method.

Rounds a value to the nearest integer or to the specified number of fractional digits.

Take a look at The Floating-Point Guide

Upvotes: 1

Praveen
Praveen

Reputation: 56501

Actually it is giving the right value.

How about getting rid of exponent after converting to float

double doubleValue = 0.00000000000000011102230246251565;
float result = (float)doubleValue;
decimal d = Decimal.Parse(result.ToString(), System.Globalization.NumberStyles.Float);

Upvotes: 1

AllTooSir
AllTooSir

Reputation: 49352

Converting double to float will definitely be loss of precision . But the value 1.110223E-16 is exponent notation i.e. raised to power -16 that means it is something like 0.0000000000000001110223.

You should use Math.Round() to round numbers.

Upvotes: 12

Bathsheba
Bathsheba

Reputation: 234635

A float is capable of representing about 6 significant figures with perfect accuracy. That's not the same thing as 6 decimal places which is what I think you were assuming.

Upvotes: 0

nvoigt
nvoigt

Reputation: 77285

The float is perfectly fine. It represents the value of the double up to the precision of a float.

1.110223E-16 is another notation for 0.0000000000000001110223.

Upvotes: 2

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