Python文本文件读写

任务：请编写程序获取data.txt文件中的数字内容。将获取的数字内容写入到data1.txt文件中，写入时在数字前添加文字注明是目标文件中的数字内容
demo.txt

Temperature data
----------------
Fahrenheit degress:67.2

demo1.txt

D:demo.txt的数字内容:67.2

import re

f = open("D:demo.txt","r",encoding="utf8")
str = f.read()
str2= float(re.findall(r'd+(?:.d+)?',str)[0])
print(str2)
w2 = open("D:demo1.txt","w",encoding="utf8")
w2.write(f"D:demo.txt的数字内容:{str2}")
f.close()

f = open("D:demo.txt","r",encoding="utf8")
str= f.readlines()
last_line = str[-1]
str2=""
num=["0","1","2","3","4","5","6","7","8","9","."]
for i in last_line:
    if i in num:
        str2+=i
print(str2)

w2 = open("D:demo1.txt", "w", encoding="utf8")
w2.write(f"D:demo.txt的数字内容:{str2}")
#w2.write("D:demo.txt的数字内容:%s" % str2),在python环境下用这个。网页版的那个太容易bug了
f.close()

笨办法是把数字和小数点写在列表里。把最后一行数字去逐一判断。如果是数字或者小数点就加到一个字符串里。因为这个文本只有一个67.2.所以这个方法不会翻车。刚好判断出来的内容就是67.2.然后写到新的文件里就ok了