IsNumeric check in linq

Question

The following linq

var subjectMarks = (from DataRow row in objDatatable.Rows
                    select Convert.ToDecimal(row["EXM_MARKS"])).Sum();

throws an exception since some row["EXM_MARKS"] has non numeric values like AB etc. How can I get the sum of only numeric ones out of them?

score 8 · Accepted Answer · answered Sep 28 '11 at 10:07

8

Add where clause that filters out the records that cannot be parsed as decimals. Try:

decimal dummy;

var subjectMarks = (from DataRow row in objDatatable.Rows
                     where decimal.TryParse(row["EXM_MARKS"], out dummy)
                     select Convert.ToDecimal(row["EXM_MARKS"])).Sum();

answered Sep 28 '11 at 10:07

Jakub Konecki

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I knw that , I am asking is ther any direct function to handle that ? – Kuntady Nithesh Sep 28 '11 at 10:08
You can select the dummy value without additional Convert.ToDecimal call – Yuriy Rozhovetskiy Sep 28 '11 at 10:16
1

@YuriyRozhovetskiy: No, you can't. This would select the value of the last row for all rows. – Daniel Hilgarth Sep 28 '11 at 10:30
if so, how you can explain this: string value = "1 a 2 b 3 c"; int dummy = 0; var digits = (from digit in value.Split(' ') where int.TryParse(digit, out dummy) select dummy).ToList(); digits.ForEach(Console.WriteLine); – Yuriy Rozhovetskiy Sep 28 '11 at 10:46
@YuriyRozhovetskiy: Yes, you are right. The deferred execution got me. – Daniel Hilgarth Sep 28 '11 at 11:20

score 5 · Answer 2 · edited Aug 11 '17 at 03:43

You could create an extension method SafeConvertToDecimal and use this in your LINQ query:

var subjectMarks = (from DataRow row in objDatatable.Rows
                    select row["EXM_MARKS"].SafeConvertToDecimal()).Sum();

This extension method would look like this:

public static decimal SafeConvertToDecimal(this object obj)
{
    decimal result;
    if(!decimal.TryParse(obj.ToString(), out result))
        result = 0;

    return result;
}

This approach has the advantage that it looks clean and you aren't converting each object twice as do all other answers.

score 1 · Answer 3 · answered Nov 14 '18 at 07:56

1

For linq to sql queries you can use built-in SqlFunctions.IsNumeric

Source: SqlFunctions.IsNumeric

answered Nov 14 '18 at 07:56

irfandar

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score 1 · Answer 4 · edited Sep 28 '11 at 10:12

1

use

Decimal Z;

var subjectMarks = (from DataRow row in objDatatable.Rows
                     where Decimal.TryParse (row["EXM_MARKS"], out Z)
                     select Convert.ToDecimal(row["EXM_MARKS"])).Sum();

edited Sep 28 '11 at 10:12

VdesmedT

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answered Sep 28 '11 at 10:11

Yahia

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score 1 · Answer 5 · answered Sep 28 '11 at 10:17

You can make some extensions utility class like this for elegant solution:

public static class TypeExtensions
{
    public static bool IsValidDecimal(this string s)
    {
        decimal result;
        return Decimal.TryParse(s, out result);
    }
}

and use it in this way:

var subjectMarks = (from DataRow row in objDatatable.Rows
                     where row["EXM_MARKS"].IsValidDecimal()
                     select Convert.ToDecimal(row["EXM_MARKS"])).Sum();

Hope this helps.

score 0 · Answer 6 · answered Nov 11 '17 at 11:31

0

var subjectMarks = objDatatable.Rows.Where(row => row["EXM_MARKS"].ToString().All(char.isDigit))

part of solution is getted in: here

answered Nov 11 '17 at 11:31

David

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result will be an array with all items numeric – David Nov 11 '17 at 11:32

IsNumeric check in linq

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