How to convert string to int?

The first row of the DataTable dt, iterates over its columns and checks if the value in any column is less than or equal to zero. If such a value is found, it throws an exception with an appropriate error message.

You can validate a row in a DataTable by iterating over the columns of the row and checking if any column's value is less than or equal to zero.
 

 // Assuming dt is the DataTable containing the row to be validated
DataRow row = dt.Rows[0]; // Get the first row

foreach (DataColumn col in dt.Columns)
{
    if (row[col] is int value && value <= 0)
    {
        // Value in column is less than or equal to zero
        // You can throw an exception, show an error message or handle it in some other way
        // For example:
        throw new Exception($"Value in column '{col.ColumnName}' is less than or equal to zero.");
    }
}

Convert.ToInt32(dt.Rows[0]["columnname"].ToString())>0