#991 – Using the Round-Trip Format Specifier

Normally, when converting a floating point value to a string, you can lose some precision.  If you then later need to convert from the string back to the original floating point data type, you could end up with a different value.  In the example below, we convert from a double to a string and then back again.  But the double that we get in the end is not equal to the original value.

            double d1 = 0.123456789123456789;
            string s1 = d1.ToString();
            double d1b = double.Parse(s1);
            bool b1 = (d1 == d1b);

991-001
You can use the “R” format specifier when converting to a string to indicate that you want to be able to convert back to a floating point value without loss of precision.

            double d1 = 0.123456789123456789;
            string s1 = d1.ToString("R");
            double d1b = double.Parse(s1);
            bool b1 = (d1 == d1b);

991-002

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About Sean
Software developer in the Twin Cities area, passionate about .NET technologies. Equally passionate about my own personal projects related to family history and preservation of family stories and photos.

One Response to #991 – Using the Round-Trip Format Specifier

  1. Pingback: Dew Drop – December 9, 2013 (#1679) | Morning Dew

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