C#t替换EXCEL字符串报错问题

xSheet.Cells.Replace(what, replace);

找到替换的会执行，找不到就会报错，有没有像WORD里的  WORD.wdreplace.replaceAll()这样的函数，这样WORD就不会报错
------解决方案--------------------

        /// <summary>

        /// 替换excel字符

        /// </summary>

        /// <param name="strOldText"></param>

        /// <param name="strNewText"></param>

        public void ExcelReplace( string strOldText, string strNewText)

        {



            int icount = wb.Sheets.Count;

                object what = strOldText; //查找字符串 



                object retxt = strNewText; //替换字符串      



                if (xSheet.Cells.Find(strOldText, Missing.Value, Missing.Value, Missing.Value, Missing.Value,

                    XlSearchDirection.xlNext, Missing.Value, Missing.Value) != null)

                {

                    for (int i = 1; i <= icount; i++)

                    {

                        xSheet = (Worksheet)wb.Sheets[i];

                    }



                    xSheet.Cells.Replace(what, retxt, Missing.Value,



                            Missing.Value, Missing.Value, Missing.Value,



                            Missing.Value, Missing.Value);

                }

        }