Get Column Name from Dataset in an array of string using c#

Question

How to get only column names from dataset in an single array of string using c#

Dataset has 17 tables, tables may have different schemas.

Answer 1

From comments

string[] names = ds.Tables.Cast<DataTable>()
    .SelectMany(x => x.Columns.Cast<DataColumn>()
        .Select(y => y.ColumnName)
    ).ToArray();