Check value of datatable with C#

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i want to check if values of datatable of the same column are equals to "int" or not , so if it's true i want to calculate with content value the sum. This is my code which return always when i click on sum button "pas tous entier" .
Thank you in advance!

What I have tried:

private void button7_Click(object sender, EventArgs e)
        {
            int i = 0, s = 0;
            String type ="int";

            DataTable dt = new DataTable("Table_insertion");

            bool exists = dt.AsEnumerable().Any(row => type == row.Field<String>("Type"));
            if (exists== true)
            {
                for (i = 0; i < dataGridView1.Rows.Count; ++i)
                {
                    s += Convert.ToInt32(dataGridView1.Rows[i].Cells[2].Value);

                }
                label5.Text = s.ToString();           
            } 
            else
            {
                MessageBox.Show("pas tous entiers");
            }
          
        }

Posted 11-Nov-19 8:05am

foreigh

Updated 12-Nov-19 5:13am

v2

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Comments

ZurdoDev 11-Nov-19 14:16pm

What are you asking us to do?

foreigh 11-Nov-19 14:32pm

to help me knowing why the sum won't be calculated and always show me the message "pas tous entiers" even if all types value are "int".

ZurdoDev 11-Nov-19 14:50pm

We can't because we can't run your code. Just debug it and see what's happening. It's very easy.

3 solutions

Solution 1

Don't use Convert functions except on values you know are valid: since you don't know if it's an integer you need to use int.TryParse instead - it returns a bool to say "converted / not valid".

C#

int value;
if (int.TryParse(dataGridView1.Rows[i].Cells[2].Value, out value))
   {
   s += value;
   }

Posted 11-Nov-19 9:14am

OriginalGriff

Comments

foreigh 11-Nov-19 16:13pm

when i try that it shows me the error =>cannot convert object to string

Solution 2

You can find out if there is an int type column like this:

bool exists = false;

foreach (DataColumn col in dt.Columns)
{
    if (col.DataType.Name == "Int32")
    {
        exists = true;
    }
}

Posted 11-Nov-19 10:12am

RickZeeland

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Richard Deeming · Accepted Answer · 2019-11-12T05:14:00

Quote:

C#

DataTable dt = new DataTable("Table_insertion");
bool exists = dt.AsEnumerable().Any(row => type == row.Field<String>("Type"));

You create a new empty DataTable, which doesn't have any rows. You then test to see whether any of the zero rows in that table match your condition.

Unsurprisingly, the answer will always be "no". :)