CODEWITHSUNDEEP
c#datatable
Calv
Calv

Reputation: 133

edit all rows in a column, data table c#

I've got a data table that's populated with data from a file that's been read in. I wish to then edit all rows in a specific column. In my case dividing the speed column by 1.6 to convert to MPH from KMH.

so far, I've tried using the below code but am getting an index out of range

foreach (DataRow row in data_table.Rows) {
     row["Speed (KM/H)"] = speed[x]/1.6;
}

here is the code that fills the data table with the file

 private void display_hrm_data() {
     /* array heart_rate_table set to heart_rate
      * adds each column
      * for every piece of data in heart_rate_table add rows
      */        
     data_table.Columns.Add("Heart Rate (BPM)", typeof(string));
     data_table.Columns.Add("Speed (KM/H)", typeof(int));
     data_table.Columns.Add("Cadence (RPM)", typeof(int));
     data_table.Columns.Add("Altitude (M)", typeof(int));
     data_table.Columns.Add("Power (Watts)", typeof(int));
     data_table.Columns.Add("Time (Seconds)", typeof(int));
     for (int x = 0; x < heart_rate.Count - 1; x++) {
         time = time + 1;
         data_table.Rows.Add(heart_rate[x],speed[x],cadence[x],altitude[x],power[x], time);
     }
     dgv_data.DataSource = data_table;
}

Upvotes: 4

Views: 2388

Answers (1)

Tim Schmelter
Tim Schmelter

Reputation: 460168

You can use the Field and SetField extensions which are strongly typed, otherwise you need to cast the fields manually from object to int. You get the IndexOutOfRange exception because x seems to be an invalid index. Use the column name.

So for example:

DataColumn speedCol = data_table.Columns["Speed (KM/H)"];
foreach (DataRow row in data_table.Rows)
{
    int oldSpeed = row.Field<int>(speedCol);
    row.SetField(speedCol, oldSpeed / 1.6); 
}

Upvotes: 2

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