#获取搜索框中的字符串
e = tkinter.Entry()
searcStr = e.get()
#是否有选中字符
is_checked = e.select_present()
checked_str = ""
if is_checked:
    #checked_str = e.select_get()    #获取选中的文本
    start_index = e.index(tkinter.ANCHOR)   #开始选择时的index
    end_index = e.index(tkinter.INSERT)     #结束选择时的index
    if start_index < end_index:
        #从左向右选择
        checked_str = searcStr[start_index : end_index]
    elif start_index > end_index:
        #从右向左选择
        checked_str = searcStr[end_index : start_index]
    else:
        checked_str = ""