os.path.isfile的错误

def DtoTab(dsrc, dtarget):
    try:
        for item in os.listdir(dsrc):
            if os.path.isfile(item):
                print(‘ok‘)

def DtoTab(dsrc, dtarget):
    try:
        for item in os.listdir(dsrc):
           
            fullfilename=os.path.join(dsrc,item)
            if os.path.isfile(fullfilename) and item.endswith(‘.txt‘):
                print(‘开始处理文件：{}‘.format(item))
                dfilename = os.path.join(dtarget,item)
                ftarget = codecs.open(dfilename, ‘w‘, encoding=‘utf-8‘)
                icount = 0
                for line in open(fullfilename, encoding=‘utf8‘):
                    line = line.replace(‘,‘, ‘\t‘)
                    icount = icount + 1
                    ftarget.write(line)
                ftarget.close()
                print(‘处理完毕文件：{}；总计{}行‘.format(item, icount))

    except Exception as e:
        print(‘出错啦，错误信息是：{}‘.format(traceback.format_exc()))