用下面这种方式打开保存对话框的时候，如何指定默认文件名？
i_ret = GetFileSaveName("导出数据",ls_filepath,ls_filename,"TXT","TXT File(*.txt),*.txt")
------解决方案--------------------
string ls_filepath, ls_filename
ls_filepath="默认文件名.txt"
i_ret = GetFileSaveName("导出数据",ls_filepath,ls_filename,"TXT","TXT File(*.txt),*.txt")