《python无师自通》第九章 文件

读写文件

st = open("pythontest.txt","w+")#可读可写模式
st.write("hi from python")
st.close()#一定要关闭

如果一直忘记关闭文件，那就试一下这个方法

with open("pythontest.txt","w+") as f:
    f.write("yes")#会把之前的内容覆盖掉

读取文件

with open("pythontest.txt","r") as f:#换成r模式
    print(f.read())

CSV模块

写入

import csv

with open("st.csv","w+",newline = '') as f:
    w = csv.writer(f,
                   delimiter=",")
    w.writerow(["one",
                "two",
                "three"])
    w.writerow(["four",
                "five",
                "six"])

读

import csv

with open("st.csv","r") as f:
    r = csv.reader(f,
                   delimiter=",")
    for row in r:
        print(",".join(row))

挑战练习

1．在计算机上找一个文件，并使用 Python 打印其内容。

with open("data.txt","r") as f:
    print(f.read())

2．编写一个程序来向用户提问，并将回答保存至文件。

a1 = input("第一个问题？")
a2 = input("第二个问题？")
a3 = input("第三个问题？")
a4 = input("第四个问题？")
list1 = [a1,a2,a3,a4]
with open("问答.txt","w+") as file:
    for i in list1:
        w = file.write(i)

3．将以下列表中的元素写入一个 CSV 文件：[[“Top Gun”, “Risky Business”,
“Minority Report”], [“Titanic”, “The Revenant”, “Inception”],
[“Training Day”, “Man on Fire”, “Flight”]]。每个列表应该在文件中各占
一行，其中元素使用逗号分隔。

import csv

with open ("练习.csv","w",newline="") as file :
    w = csv.writer(file,
                  delimiter = ",")
    w.writerow(["Top Gun", "Risky Business", "Minority Report"])
    w.writerow(["Titanic", "The Revenant", "Inception"])
    w.writerow(["Training Day", "Man on Fire", "Flight"])