How to read a decimal value of order 0.000e-6 from a SqlDataReader in C# double variable

Question

I am trying to read some decimal values from my DB. These values are the order of 10^-6. I am trying to read it into a double variable in C# using code like this: sqltype in database is "float". sample value to be read is "1.99999999495049E-06" –

Double [] rmseValues = null;

while (dataReader.Read())
{
    // This shows my datatype is float (sql)
    string temp = dataReader.GetDataTypeName(0);

    // This returns a value of "0"
    string temp1 = dataReader.GetOrdinal("RmseAll").ToString();

    // This throws exception of invalid typecast
    rmseValues[0] = dataReader.GetFloat(0);
}

@AnujDubey I suspect you should actually be using a decimal here... what is the sql type in the database, and what does the value represent? — Marc Gravell
– Marc Gravell, Commented Aug 24, 2015 at 8:25

MRebai · Accepted Answer · 2015-08-24 09:03:49Z

1

Try to use GetDouble(0) instead of GetFloat(0)

I think you will also need to edit that line :

Double [] rmseValues = null;

In fact your are trying to put values inside a null object as solution you need to initialize your rmseValues array or just use a List of double

Double[] rmseValues = new Double[10];

edited Aug 24, 2015 at 9:03

answered Aug 24, 2015 at 8:28

MRebai

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7 Comments

AnujDubey Over a year ago

that throws an exception "{"Object reference not set to an instance of an object."}"

Lasse V. Karlsen Over a year ago

That is a different problem, you need to show the code in this case.

Marc Gravell Over a year ago

@AnujDubey if rmseValues[0] = dataReader.GetFloat(0); throws a typecase exception, and rmseValues[0] = dataReader.GetDouble(0); throws a null-reference exception, then: rmseValues is null - so go fix that

Marc Gravell Over a year ago

@LasseV.Karlsen I'm guessing Double [] rmseValues = null; isn't helping ;p

Lasse V. Karlsen Over a year ago

Still had the old copy of the question on my screen, that explains it.

|

Nissim · Accepted Answer · 2015-08-24 08:23:14Z

0

Use GetInt64(0) instead of GetFloat(0)

answered Aug 24, 2015 at 8:23

Nissim

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1 Comment

Marc Gravell Over a year ago

That wouldn't help store a value like the one cited

Dmitrii Bychenko · Accepted Answer · 2015-08-24 12:14:58Z

0

In order not be dependent on RDBMS actual background type (say, NUMBER(10, 3) or alike) and its representation as .Net Type (e.g. Single) do a conversion:

  // rmseValues[0] should be Double
  rmseValues[0] = Convert.ToDouble(dataReader.GetValue(0));

edited Aug 24, 2015 at 12:14

answered Aug 24, 2015 at 8:33

Dmitrii Bychenko

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