How To: Best way to draw table in console app (C#)

Edit: thanks to @superlogical, you can now find and improve the following code in github!


I wrote this class based on some ideas here. The columns width is optimal, an it can handle object arrays with this simple API:

static void Main(string[] args)
{
  IEnumerable<Tuple<int, string, string>> authors =
    new[]
    {
      Tuple.Create(1, "Isaac", "Asimov"),
      Tuple.Create(2, "Robert", "Heinlein"),
      Tuple.Create(3, "Frank", "Herbert"),
      Tuple.Create(4, "Aldous", "Huxley"),
    };

  Console.WriteLine(authors.ToStringTable(
    new[] {"Id", "First Name", "Surname"},
    a => a.Item1, a => a.Item2, a => a.Item3));

  /* Result:        
  | Id | First Name | Surname  |
  |----------------------------|
  | 1  | Isaac      | Asimov   |
  | 2  | Robert     | Heinlein |
  | 3  | Frank      | Herbert  |
  | 4  | Aldous     | Huxley   |
  */
}

Here is the class:

public static class TableParser
{
  public static string ToStringTable<T>(
    this IEnumerable<T> values,
    string[] columnHeaders,
    params Func<T, object>[] valueSelectors)
  {
    return ToStringTable(values.ToArray(), columnHeaders, valueSelectors);
  }

  public static string ToStringTable<T>(
    this T[] values,
    string[] columnHeaders,
    params Func<T, object>[] valueSelectors)
  {
    Debug.Assert(columnHeaders.Length == valueSelectors.Length);

    var arrValues = new string[values.Length + 1, valueSelectors.Length];

    // Fill headers
    for (int colIndex = 0; colIndex < arrValues.GetLength(1); colIndex++)
    {
      arrValues[0, colIndex] = columnHeaders[colIndex];
    }

    // Fill table rows
    for (int rowIndex = 1; rowIndex < arrValues.GetLength(0); rowIndex++)
    {
      for (int colIndex = 0; colIndex < arrValues.GetLength(1); colIndex++)
      {
        arrValues[rowIndex, colIndex] = valueSelectors[colIndex]
          .Invoke(values[rowIndex - 1]).ToString();
      }
    }

    return ToStringTable(arrValues);
  }

  public static string ToStringTable(this string[,] arrValues)
  {
    int[] maxColumnsWidth = GetMaxColumnsWidth(arrValues);
    var headerSpliter = new string('-', maxColumnsWidth.Sum(i => i + 3) - 1);

    var sb = new StringBuilder();
    for (int rowIndex = 0; rowIndex < arrValues.GetLength(0); rowIndex++)
    {
      for (int colIndex = 0; colIndex < arrValues.GetLength(1); colIndex++)
      {
        // Print cell
        string cell = arrValues[rowIndex, colIndex];
        cell = cell.PadRight(maxColumnsWidth[colIndex]);
        sb.Append(" | ");
        sb.Append(cell);
      }

      // Print end of line
      sb.Append(" | ");
      sb.AppendLine();

      // Print splitter
      if (rowIndex == 0)
      {
        sb.AppendFormat(" |{0}| ", headerSpliter);
        sb.AppendLine();
      }
    }

    return sb.ToString();
  }

  private static int[] GetMaxColumnsWidth(string[,] arrValues)
  {
    var maxColumnsWidth = new int[arrValues.GetLength(1)];
    for (int colIndex = 0; colIndex < arrValues.GetLength(1); colIndex++)
    {
      for (int rowIndex = 0; rowIndex < arrValues.GetLength(0); rowIndex++)
      {
        int newLength = arrValues[rowIndex, colIndex].Length;
        int oldLength = maxColumnsWidth[colIndex];

        if (newLength > oldLength)
        {
          maxColumnsWidth[colIndex] = newLength;
        }
      }
    }

    return maxColumnsWidth;
  }
}

Edit: I added a minor improvement - if you want the column headers to be the property name, add the following method to TableParser (note that it will be a bit slower due to reflection):

public static string ToStringTable<T>(
    this IEnumerable<T> values,
    params Expression<Func<T, object>>[] valueSelectors)
{
  var headers = valueSelectors.Select(func => GetProperty(func).Name).ToArray();
  var selectors = valueSelectors.Select(exp => exp.Compile()).ToArray();
  return TableParser.ToStringTable(values, headers, selectors);
}

private static PropertyInfo GetProperty<T>(Expression<Func<T, object>> expresstion)
{
  if (expresstion.Body is UnaryExpression)
  {
    if ((expresstion.Body as UnaryExpression).Operand is MemberExpression)
    {
      return ((expresstion.Body as UnaryExpression).Operand as MemberExpression).Member as PropertyInfo;
    }
  }

  if ((expresstion.Body is MemberExpression))
  {
    return (expresstion.Body as MemberExpression).Member as PropertyInfo;
  }
  return null;
}

Use String.Format with alignment values.

For example:

String.Format("|{0,5}|{1,5}|{2,5}|{3,5}|", arg0, arg1, arg2, arg3);

To create one formatted row.


You could do something like the following:

static int tableWidth = 73;

static void Main(string[] args)
{
    Console.Clear();
    PrintLine();
    PrintRow("Column 1", "Column 2", "Column 3", "Column 4");
    PrintLine();
    PrintRow("", "", "", "");
    PrintRow("", "", "", "");
    PrintLine();
    Console.ReadLine();
}

static void PrintLine()
{
    Console.WriteLine(new string('-', tableWidth));
}

static void PrintRow(params string[] columns)
{
    int width = (tableWidth - columns.Length) / columns.Length;
    string row = "|";

    foreach (string column in columns)
    {
        row += AlignCentre(column, width) + "|";
    }

    Console.WriteLine(row);
}

static string AlignCentre(string text, int width)
{
    text = text.Length > width ? text.Substring(0, width - 3) + "..." : text;

    if (string.IsNullOrEmpty(text))
    {
        return new string(' ', width);
    }
    else
    {
        return text.PadRight(width - (width - text.Length) / 2).PadLeft(width);
    }
}