How to loop through all rows of the DataTable?

I know this tip is very easy for 6 month experienced professionals but still some time few new professional are looking for this tip.

foreach (DataRow row in dTable.Rows)
{
yourvariable = row["ColumnName"].ToString();
}

//OR
for (int j = 0; j< dTable.Rows.Count; j++)
{
yourvariable = dTable.Rows[j]["ColumnName"].ToString()l
}