C#替换Word文本框中的内容（不使用Bookmark）

/// <summary>
/// 查找并替换文本
/// </summary>
/// <param name="wordApp"></param>
/// <param name="oldStr"></param>
/// <param name="newStr"></param>
public void SearchReplace(string oldStr, string newStr)
{
        #region 文字区域
        object replaceAll = WdReplace.wdReplaceAll;

        wordApp.Selection.Find.ClearFormatting();
        wordApp.Selection.Find.Text = oldStr;

        wordApp.Selection.Find.Replacement.ClearFormatting();
        wordApp.Selection.Find.Replacement.Text = newStr;

        wordApp.Selection.Find.Execute(
                ref missing, ref missing, ref missing, ref missing, ref missing,
                ref missing, ref missing, ref missing, ref missing, ref missing,
                ref replaceAll, ref missing, ref missing, ref missing, ref missing);
        #endregion

        #region 文本框
        StoryRanges sr = wordDoc.StoryRanges;
        foreach (Range r in sr)
        {
                Range r1 = r;
                if (WdStoryType.wdTextFrameStory == r.StoryType)
                {
                        do
                        {
                                r1.Find.ClearFormatting();
                                r1.Find.Text = oldStr;

                                r1.Find.Replacement.ClearFormatting();
                                r1.Find.Replacement.Text = newStr;

                                r1.Find.Execute(
                                        ref missing, ref missing, ref missing, ref missing, ref missing,
                                        ref missing, ref missing, ref missing, ref missing, ref missing,
                                        ref replaceAll, ref missing, ref missing, ref missing, ref missing);

                                r1 = r1.NextStoryRange;
                        } while (r1 != null);
                }
        }
        #endregion
}