python异常处理，草稿

import traceback
def calc(a,b):
   res = a/b
   return res

def main():
   money = input('输入多少钱：')
   months = input('还几个月：')
   try:
      res = calc(int(money),int(months))
   except ZeroDivisionError as e:  #try里面的代码如果出错了，走except里面的代码,ZeroDivisionError是从报错中取的，如下图
      traceback.print_exc()#traceback只是输出报错的详细信息而已，红体字，不影响代码运行
      print('还款的月数不能小于1',e)
   except ValueError as e:
      print('输入必须是整数，%s'%e)
   except Exception as e:  #捕获所有的异常，放在异常处理最后
      print('未知错误！%s'%e)
   else:#没有出错的情况下走else
      print('每个月应该还%s'%res)
   print('hahahahahahah')

import pymysql
def main2(sql):
   try:
      conn=pymysql.connect(host='122.932.122.11',user='root',password='123456',db='test')
   except Exception as e:
      print('数据库连接不了，%s'%e)
   else:
      cur = conn.cursor()
      try:
         cur.execute(sql)
      except Exception as e:
         print('sql语句有错误！%s。sql是"%s'%(e,sql))
      else:
         res = cur.fetchall()
         return res
      finally: #不管有没有捕捉到异常，都会走这里finally。
         cur.close()
         conn.close()


# try:
#  a = int(input('xx:'))
#  b = int(input('sss:'))
#  res = a/b
# except Exception as e:
#  print(e)
# else:
#  print(res)
# finally:
#  print('什么时候到我这里呢')
import requests
def req():
   r = requests.get('http://api.nnzhp.cn/api/user/all_stu',headers={'Referer':'http://api.nnzhp.cn/'})
   if len(r.json()['stu_info'])<0:
      pass
   else:
      raise Exception('接口没数据') #主动抛出异常raise

req()