python中csv文件的读写

with open("test.csv","w") as c:
writer=csv.writer(c)
writer.writerow(['name','address','city','state'])

l=[]
l.append([1,2,3])
l.append([4,5,6])
l.append([7,8,9])
with open("test.csv","w") as c1:
writer=csv.writer(c1)
for idx in l:
writer.writerow(idx)

with open("test.csv","r") as c1:
lines=csv.reader(c1)
for line in lines:
print(line)