python CSV文件操作

import csv
f=open(r'test.csv','w+',newline='')
list=[[1,2,3],[4,5,6],[7,8,9]]
c=csv.writer(f,dialect='excel')
l=len(list)
for i in range(0,l):
    c.writerow(list[i])
f.close()
r=csv.reader(open(r"test.csv",encoding="utf-8"))
for row in r:
    print(row)