/// <summary>
/// Retrieve column position by name in first row.
/// </summary>
/// <param name="sheet">Page to find column</param>
/// <param name="columnName">Name to find column in first row</param>
/// <returns>Position of column name or 0 when not found</returns>
/// <exception cref="ArgumentNullException">When <paramref name="columnName"/> is null o whitespace</exception>
public static int ColumnByName(this IXLWorksheet sheet, string columnName)
{
if (string.IsNullOrWhiteSpace(columnName))
{
throw new ArgumentNullException(nameof(columnName), "Enter the column name to get position.");
}
if (sheet.RowCount() <= 0)
{
return(0);
}
for (var i = 1; i <= sheet.ColumnUsedCount(); i++)
{
if (sheet.Row(1).Cell(i).Value.ToString()?.ToUpper() == columnName.ToUpper())
{
return(i);
}
}
return(0);
}