C#

public class MultiColourDataGridViewTextBoxCell : DataGridViewTextBoxCell
    {
        public MultiColourDataGridViewTextBoxCell():base()
        {
        }

        /// <summary>
        /// overide paint method to colour text dependant on number of consecutive numbers
        /// </summary>
        /// <param name="graphics"></param>
        /// <param name="clipBounds"></param>
        /// <param name="cellBounds"></param>
        /// <param name="rowIndex"></param>
        /// <param name="cellState"></param>
        /// <param name="value"></param>
        /// <param name="formattedValue"></param>
        /// <param name="errorText"></param>
        /// <param name="cellStyle"></param>
        /// <param name="advancedBorderStyle"></param>
        /// <param name="paintParts"></param>
        protected override void Paint(Graphics graphics, Rectangle clipBounds, Rectangle cellBounds, int rowIndex, DataGridViewElementStates cellState, object value, object formattedValue, string errorText, DataGridViewCellStyle cellStyle, DataGridViewAdvancedBorderStyle advancedBorderStyle, DataGridViewPaintParts paintParts)
        {
            int fontSize = 9;
            Brush textBrush = Brushes.Green;
            Font font = new Font(FontFamily.GenericSansSerif,fontSize,FontStyle.Regular);
            String stringPrint = (String)formattedValue;

            graphics.FillRectangles(Brushes.White,new Rectangle[]{cellBounds});
            StringPrintInfo[] stringPrintInfo = GetConsectiveNumbers(4, stringPrint, Brushes.Black, Brushes.Red);
            PrintConsectiveNumbers(stringPrintInfo,graphics, font,textBrush,cellBounds,StringFormat.GenericDefault);
            this.PaintBorder(graphics, clipBounds, cellBounds, cellStyle, advancedBorderStyle);

        }

        /// <summary>
        /// from input string finds consective numbers marjs them in specified colour.
        /// </summary>
        /// <param name="numberConsecutive">number of consecutive numbers to look for</param>
        /// <param name="input">input string</param>
        /// <param name="bOriginal">default brush colour</param>
        /// <param name="bConsecutive">brush for consecutive numbers</param>
        /// <returns> an ordered array of text and colour pairs</returns>
        public StringPrintInfo[] GetConsectiveNumbers(int numberConsecutive, String input, Brush bOriginal, Brush bConsecutive)
        {
            List<StringPrintInfo> formatInformation = new List<StringPrintInfo>();
            int inputCount = 0; //how much of input string is used
            StringPrintInfo tmpStrPrntInfo;
            String regExp = "\\b[0-9]{4}\\b";

            Regex exp = new Regex(regExp);
            foreach (Match match in exp.Matches(input))
            {

                if (inputCount < match.Index)
                {
                    tmpStrPrntInfo = new StringPrintInfo();
                    String strTmp = input.Substring(0, match.Index);
                    tmpStrPrntInfo.str = strTmp;
                    tmpStrPrntInfo.brush = bOriginal;
                    inputCount = match.Index;
                    formatInformation.Add(tmpStrPrntInfo);
                }

                tmpStrPrntInfo = new StringPrintInfo();
                tmpStrPrntInfo.str = match.Value;
                tmpStrPrntInfo.brush = bConsecutive;
                inputCount = match.Index + match.Length;
                formatInformation.Add(tmpStrPrntInfo);
            }

            if (inputCount < input.Length)
            {
                tmpStrPrntInfo = new StringPrintInfo();
                String strTmp = input.Substring(inputCount);
                tmpStrPrntInfo.str = strTmp;
                tmpStrPrntInfo.brush = bOriginal;
                inputCount = input.Length;
                formatInformation.Add(tmpStrPrntInfo);
            }

            return formatInformation.ToArray();
        }

        /// <summary>
        /// Prints the cell with multicolour text. should be called as part of paint method
        /// </summary>
        /// <param name="toPrint"></param>
        /// <param name="graphics"></param>
        /// <param name="font"></param>
        /// <param name="textBrush"></param>
        /// <param name="cellBounds"></param>
        /// <param name="stringFormat"></param>
        public void PrintConsectiveNumbers(StringPrintInfo[] toPrint,Graphics graphics, Font font ,Brush textBrush,Rectangle cellBounds, StringFormat stringFormat)
        {
            float xOffset = 0;

            for(int i = 0;i<toPrint.Length;i++)
            {

                if (i > 0)
                {
                    SizeF stringSize = graphics.MeasureString(toPrint[i-1].str, font);
                    xOffset += stringSize.Width;
                }

                /*dont print of edges of cell*/
                if (cellBounds.X+ xOffset + graphics.MeasureString(toPrint[i].str, font).Width > cellBounds.X + cellBounds.Width)
                {
                    string cutDown = toPrint[i].str;

                    for (int j = cutDown.Length; j > 0; j--)
                    {
                        cutDown = cutDown.Substring(0, j);
                        if (cellBounds.X + xOffset + graphics.MeasureString(cutDown, font).Width <= cellBounds.X + cellBounds.Width)
                        {
                            graphics.DrawString(cutDown, font, toPrint[i].brush, cellBounds.X + xOffset, cellBounds.Y, stringFormat);
                            break;
                        }
                    }
                }
                else
                {
                    graphics.DrawString(toPrint[i].str, font, toPrint[i].brush, cellBounds.X + xOffset, cellBounds.Y, stringFormat);

                }
            }
            
        }

        /// <summary>
        /// represent string to print and colour to print it
        /// </summary>
        public struct StringPrintInfo
        {
            public String str;
            public Brush brush;
        }
    }

//DataSet
DataSet dataSet = new DataSet();
DataTable dStable = new DataTable();
DataColumn dSCol1 = new DataColumn("name", typeof(string));
DataColumn dSCol2 = new DataColumn("value", typeof(string));
DataRow rTemp;

//DataGridView
DataGridViewColumnCollection dGVColumnCollection;
DataGridViewColumn dGVColumn1 = new DataGridViewColumn();
DataGridViewColumn dGVColumn2 = new DataGridViewColumn();

public partial class Form1 : Form
{
    //DataSet
    DataSet dataSet = new DataSet();
    DataTable dStable = new DataTable();
    DataColumn dSCol1 = new DataColumn("name", typeof(string));
    DataColumn dSCol2 = new DataColumn("value", typeof(string));
    DataRow rTemp;

    //DataGridView
    DataGridViewColumnCollection dGVColumnCollection;
    DataGridViewColumn dGVColumn1 = new DataGridViewColumn();
    DataGridViewColumn dGVColumn2 = new DataGridViewColumn();



    public Form1()
    {
        InitializeComponent();

        //initialise dataset
        dStable.TableName = "sample";
        dStable.Columns.Add(dSCol1);
        dStable.Columns.Add(dSCol2);
        rTemp = dStable.NewRow();
        rTemp.ItemArray = new object[]{"bill", " 000 0000 0000000 0000000 0000000000"};
        dStable.Rows.Add(rTemp);
        rTemp = dStable.NewRow();
        rTemp.ItemArray = new object[]{"ted", " 111 1111 1111111 1111111 1111111111"};
        dStable.Rows.Add(rTemp);
        rTemp = dStable.NewRow();
        rTemp.ItemArray = new object[] { "john", " 222 2222 2222222 2222222 2222222222" };
        dStable.Rows.Add(rTemp);
        dataSet.Tables.Add(dStable);

        //add coloumns to datagridView
        dGVColumnCollection = dataGridView1.Columns;
        dGVColumnCollection.Add("col1", "Name");
        dGVColumnCollection.Add("col2", "Value");
        dGVColumn1 = dGVColumnCollection[0];
        dGVColumn2 = dGVColumnCollection[1];


        //pupulate DataGridView
        foreach(DataRow row in dataSet.Tables[0].Rows)
        {
            DataGridViewRow dGVRow = new DataGridViewRow();
            DataGridViewTextBoxCell textCell = new DataGridViewTextBoxCell();
            MultiColourDataGridViewTextBoxCell textCel2 = new MultiColourDataGridViewTextBoxCell();
            textCell.Value = row.ItemArray[0];
            textCel2.Value = row.ItemArray[1];
            dGVRow.Cells.Add(textCell);
            dGVRow.Cells.Add(textCel2);
            dataGridView1.Rows.Add(dGVRow);
        }

    }
}

Paul Harsent wrote:

the line isnt working

if(!mail)
   {
   if ((text != ""))
      {
      int indexofTO = text.IndexOf("to");
      int indexofSLOT = text.IndexOf("Slot");
      if (indexofSLOT < indexofTO) //load
         {
         ...
         }
      }
   }

if(!mail)
{
if ((text != ""))
{
int indexofTO = text.IndexOf("to");
int indexofSLOT = text.IndexOf("Slot");
if (indexofSLOT < indexofTO) //load
{
...
}
}
}