Learn Python the Hard Way 15 Reading Files

用 Python 來讀取檔案

這次來練習怎麼讀取檔案，我們先來建立一個 txt 檔，檔案名稱就叫 ex15_sample.txt 吧，內容如下，亂打也沒差。

This is stuff I typed in to a file.
It is really cool stuff.
Lots and lots of fun to have in here.

接著今天的 code：

from sys import argv
script, filename = argv
txt = open(filename)
print(f"Here's your file {filename}:")
print(txt.read())
print("Type the filename again:")
file_again = input("> ")
txt_again = open(file_again)
print(txt_again.read())

在這邊我們用了 open() 來打開我們的檔案，用 read () 來讀取裡面的內容。

我們在 terminal 輸入：

python ex15.py ex15_sample.txt

會得到輸出 (我在文檔多加了兩行空行)：

Here's your file ex15_sample.txt:
This is stuff I typed in to a file.
It is really cool stuff.
Lots and lots of fun to have in here.
Type the filename again:
> ex15_sample.txt
This is stuff I typed in to a file.
It is really cool stuff.
Lots and lots of fun to have in here.

利用 comment 來解釋 code：

#import argv
from sys import argv

# 將 argv 分成 script, filename 兩個變數
script, filename = argv
# 使用 open() 來建立 file object
txt = open(filename)
# 使用 read() 讀取裡面的內容
print(f"Here's your file {filename}:")
print(txt.read()) 
print("Type the filename again:")
file_again = input("> ")
txt_again = open(file_again)
print(txt_again.read())

另外，用 open() 開啟文件，也有 close() 來關閉文件，當我們沒要使用該文件時，要養成一個好習慣就是關閉它，以免不小心讀取到又修改裡面的內容，close () 可以這樣用：

txt = open(filename)
print(f"Here's your file {filename}:")
print(txt.read()) 
txt.close()

這系列文章的練習，都是來自於 Learn Python the Hard Way 這本書中，內容只針對練習做紀錄和自己的心得分享，為保護著作權故沒有透露太多內容，能力可及的話還是鼓勵大家買一本來自行練習，有問題都可以在下方進行討論。

Learn Python the Hard Way 系列文章

1. Part 1 — Printing, String, Variable

2. Part 2 — Data Interaction

3. Part 3 — Function

4. Part 4 — String, Bytes, and Character Encodings

5. Part 5 — Logic and Loop

6. Part 6 — Data Structure and Class