python中txt保存不了





import requests
import csv
from lxml import etree

def amd():

    for i in range(1,6):
        url = "http://www.spiderbuf.cn/beginner?level=4&pageno={}".format(i)
        print(url)
        header = {
            "user-agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/113.0.0.0 Safari/537.36"
        }
        response = requests.get(url=url,headers=header).text
        # s1 = ".*?"
        # asd = re.compile(s1,response)
        # print(asd)
        # f = open("01.html","w",encoding="utf8")
        # f.write(response)
        # f.close()

        s2 = etree.HTML(response)
        # s3 = s2.xpath('//tr/td/text()')
        # for td in s3:
        #     ts = td + "|"
        #     print(ts)

        s3 = s2.xpath('//tr/td')
        s = ""
        for j in s3:
            # s = s + str(j.text()) + "|"
            """
            在字符串里面text后面不能加()
            """
            # s = s + str(j.text) + "|"
            """
            最大的改变在这里，
            """
            s = s + str(j.xpath("string(.)")) + "|"
            # 此处的string会绕过一些干扰直接去提取
        print("--------以下为第%d页数--------"%(i))
        print(s)

        with open("训练3.csv","a+",newline="",encoding="utf8") as fin:
                writes = csv.writer(fin)
                writes.writerow(s)
# 上面的csv文件能存进去

"""
对比csv文件和txt文件的写入方式
"""
        with open("训练3.txt","a+",encoding="utf8") as fins:
                fins.writelines(s)

# f = open("01.html","w",encoding="utf8")
# f.write(td)
# f.close()
if __name__ == '__main__':
    amd()

而在txt文件中保存时，提示没有定义变量s，怎么回事？缩进了取消都一样

![img](https://img-mid.csdnimg.cn/release/static/image/mid/ask/956493124586176.png "#left")



import requests
import csv
from lxml import etree

def amd():

    for i in range(1,6):
        url = "http://www.spiderbuf.cn/beginner?level=4&pageno={}".format(i)
        print(url)
        header = {
            "user-agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/113.0.0.0 Safari/537.36"
        }
        response = requests.get(url=url,headers=header).text

        s2 = etree.HTML(response)
        s3 = s2.xpath('//tr/td')
        s = ""
        for j in s3:
            s += str(j.xpath("string(.)")) + "|"
        print("--------以下为第%d页数--------"%(i))
        print(s)

        with open("训练3.csv","a+",newline="",encoding="utf8") as fin:
            writes = csv.writer(fin)
            writes.writerow(s)

        with open("训练3.txt","a+",encoding="utf8") as fins:
            fins.write(s + "\n") # add a newline character at the end of each line

if __name__ == '__main__':
    amd()

没有在循环之前定义变量 s

def amd():
    s = ""
    for i in range(1,6):
    # ...省略部分代码...