RichText实现动态输入关键字高亮颜色显示

        int a = 0;
        string[] kc = new string[40] { "private","protected","public","namespace","class","object","if","else",
                                       "while","switch","case","using","eventargs","return","null","void","int",
                                       "string","float","char","this","set","new","true","false","const",
                                        "static","internal","extends","super","import","default","break",
                                        "try","catch","finally","main","writeline","console","writeLine"    }; 

        private void timer1_Tick(object sender, EventArgs e)
        {
            a = changeColor(kc);
            timer1.Enabled = false;
        }
        /// <summary>
        /// 改变richTextBox中指定字符串的颜色
        /// 调用即可
        /// </summary>
        /// <param name="str" value="为指定的字符串"></param>

        public int changeColor(string[] str)
        {
            ArrayList list = null;
            int b = 0;
            for (int i = 0; i < str.Length; i++)
            {
                list = getIndexArray(richTextBox1.Text.ToLower(), str[i]);
                b += list.Count;
            }
            for (int i = 0; i < str.Length; i++)
            {
                list = getIndexArray(richTextBox1.Text.ToLower(), str[i]);
                if (list.Count == 0)
                {
                    continue;
                }
                if (a == b)
                {
                    richTextBox1.SelectionColor = Color.Empty;
                    return b;
                }
                for (int j = 0; j < list.Count; j++)
                {
                    int index = (int)list[j];
                    richTextBox1.Select(index, str[i].Length);
                    richTextBox1.SelectionColor = Color.Blue;
                    this.richTextBox1.Focus();
                    //设置光标的位置到文本尾 
                    this.richTextBox1.Select(this.richTextBox1.TextLength, 0);
                    //滚动到控件光标处
                    this.richTextBox1.ScrollToCaret();
                    richTextBox1.SelectionColor = Color.Empty;
                }
            }
            return b;
        }

        public ArrayList getIndexArray(String inputStr, String findStr)
        {
            ArrayList list = new ArrayList();
            int start = 0;
            while (start < inputStr.Length)
            {
                int index = inputStr.IndexOf(findStr, start);
                if (index >= 0)
                {
                    list.Add(index);
                    start = index + findStr.Length;
                }
                else
                {
                    break;
                }
            }
            return list;
        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            timer1.Enabled = true;
        }