Python实现计算两个时间之间相差天数的方法

#-*- encoding:UTF-8 -*-from datetime import dateimport timenowtime = date.today()def convertstringtodate(stringtime):  "把字符串类型转换为date类型"  if stringtime[0:2] == "20":    year=stringtime[0:4]    month=stringtime[4:6]    day=stringtime[6:8]    begintime=date(int(year),int(month),int(day))    return begintime  else :    year="20"+stringtime[0:2]    month=stringtime[2:4]    day=stringtime[4:6]    begintime=date(int(year),int(month),int(day))    return begintimedef comparetime(nowtime,stringtime):  "比较两个时间,并返回两个日期之间相差的天数"  if isinstance(nowtime,date):    pass  else:    nowtime=convertstringtodate(nowtime)  if isinstance(stringtime,date):    pass  else:    stringtime=convertstringtodate(stringtime)  result=nowtime-stringtime  return result.days"""  if stringtime[0:2] == "20":    year=stringtime[0:4]    month=stringtime[4:6]    day=stringtime[6:8]    begintime=date(int(year),int(month),int(day))    endtime=nowtime    result=endtime-begintime    return result.days  else :    year="20"+stringtime[0:2]    month=stringtime[2:4]    day=stringtime[4:6]    begintime=date(int(year),int(month),int(day))    endtime=nowtime    result=endtime-begintime    return result.days"""print isinstance("20141012",date)print comparetime(nowtime,"140619")