srting does not convert in null value in c#

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i am converting string to null value but it returns 0 but i want null value instead of 0.

my code is

C#

public decimal? HwareCost { get; set; }

decimal tmpHwareCost = 0.0m;
if (Decimal.TryParse(Convert.ToString((dataRow["HwareCost"])), out tmpHwareCost))
itAreaList.HwareCost = tmpHwareCost;

plz help me

Posted 16-Dec-14 19:50pm

sanjaysgh

Updated 16-Dec-14 19:52pm

Praveen Kumar Upadhyay

v3

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Praveen Kumar Upadhyay · Answer 1 · 2014-12-16T20:06:00

Solution 1

There are few things in your code to notice.

C#

1)Convert.ToString(dataRow["HwareCost"])

It will convert the object and will return the string and if object is null then it returns a blank/empty string.

C#

2)Decimal.TryParse

It will try to convert the object into decimal and if object is null then it will assign 0 to out variable.

If you want to have a null object into your decimal property then do the code like this.

C#

if(!Convert.IsDBNull(dataRow["HwareCost"]))
{
   itAreaList.HwareCost = Convert.ToDecimal(dataRow["HwareCost"]);
}
else
{
   itAreaList.HwareCost =  null;
}

Posted 16-Dec-14 20:06pm

Praveen Kumar Upadhyay

Updated 16-Dec-14 20:08pm

v2

Comments

Maciej Los 17-Dec-14 2:20am

Using IsDbNull or DbNull.Value is very good practice.
+5!

Praveen Kumar Upadhyay 17-Dec-14 2:32am

Thank you Maciej.

DamithSL 17-Dec-14 2:44am

Maciej, we can use Field extension method and get the value directly without all these validations

Maciej Los 17-Dec-14 3:08am

Good point!

Praveen Kumar Upadhyay 17-Dec-14 3:12am

Even I am agree with your point.

DamithSL · Answer 2 · 2014-12-16T20:17:00

DataRow Field extension method as below[^]

C#

HwareCost = dataRow.Field<decimal?>("HwareCost");

LINQPAD sample code:

C#

decimal? HwareCost1 { get; set; }
decimal? HwareCost2 { get; set; }
void Main()
{
	var table = GetTable();
        //read first row value 
	HwareCost1 = table.Rows[0].Field<decimal?>("HwareCost") ;
	//HwareCost1.Dump(); //25.44
        //read 2nd row value 
	HwareCost2 = table.Rows[1].Field<decimal?>("HwareCost") ;
	//HwareCost2.Dump(); //null
}

static DataTable GetTable()
{
	DataTable table = new DataTable();
	DataColumn column;
	column = new DataColumn("HwareCost", 
	System.Type.GetType("System.Decimal"));
	column.AllowDBNull = true;
	table.Columns.Add(column);
	table.Columns.Add("Date", typeof(DateTime));
	table.Rows.Add(25.44m,DateTime.Now);
	table.Rows.Add(null,DateTime.Now);
	return table;
}

/\jmot · Answer 3 · 2014-12-16T20:27:00

Solution 3

try..

C#

if (!String.IsNullorEmpty(Convert.ToString((dataRow["HwareCost"])))
{
 itAreaList.HwareCost = Convert.ToDecimal((dataRow["HwareCost"]);
}
else
{
itAreaList.HwareCost=null;
}

Posted 16-Dec-14 20:27pm

/\jmot