operator += cannot be applied to operands of type object and object

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Dear all

i have problem with this bit of coding

C#

dr["DataColumn1"] += dtshort.Rows[0][0];

when i pass value to dtshort.Rows[0][0]=1, it ll store dr["DataColumn1"] it fine but my prob is when i am using loop i want continuously add value to dr["DataColumn1"]

How to do this,...

Posted 7-Dec-14 22:33pm

prasanna.raj

Updated 7-Dec-14 22:34pm

v2

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2 solutions

Solution 1

1. The values get from the data source by using DataReader are in fact boxed objects and they should be unboxed to their original types like in the next example:

C#

string name = (string)dr["DataColumn1"];
double number = (double)dr["DataColumn2"];

2.For more details about boxing and unboxing see in MSDN:http://msdn.microsoft.com/en-us/library/yz2be5wk.aspx[^]

Posted 7-Dec-14 22:40pm

Raul Iloc

Updated 7-Dec-14 22:41pm

v2

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prasanna.raj 8-Dec-14 4:52am

Thanks for replay and my query is i want add values to dr["DataColumn1"]
for example

dr["DataColumn1"] += dtshort.Rows[0][0] this dtshort.Rows[0][0] returns value 1,2,3, so how to add this value(6) to dr["DataColumn1"]

Raul Iloc 8-Dec-14 6:31am

You should use a temp value, of type "int", in your loop to accumulate the sum of all your rows, then to save the final result into your "dr" object.

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Kornfeld Eliyahu Peter · Accepted Answer · 2014-12-07T22:43:00

Solution 2

dr["DataColumn1"] can handle different types of data, to do that its type set to object (after all everything is an object).
However object do not implement the operator of += as this is a common type and += operator can be very different for different actual types (imagine 1+1 and '1'+'1')...
What you can do is convert dr["DataColumn1"] to it's expected type and than apply += operator:

C#

int n = Convert.ToInt32(dr["DataColumn1"]);
dr["DataColumn1"] = n + Convert.ToInt32(dtshort.Rows[0][0]);

Posted 7-Dec-14 22:43pm

Kornfeld Eliyahu Peter

Updated 7-Dec-14 23:00pm

v2

Comments

prasanna.raj 8-Dec-14 4:57am

Hi, i got this error ! The left-hand side of an assignment must be a variable, property or indexer

Kornfeld Eliyahu Peter 8-Dec-14 5:01am

Updated...

prasanna.raj 8-Dec-14 7:57am

Thanks i got it...

Kornfeld Eliyahu Peter 8-Dec-14 8:01am

You are welcome!