檔案 IO
file
不再是 3.x 中的內建名稱(open
仍然有效)。
檔案 I / O 的內部細節已經移動到標準庫 io
模組,這也是 StringIO
的新家:
import io
assert io.open is open # the builtin is an alias
buffer = io.StringIO()
buffer.write('hello, ') # returns number of characters written
buffer.write('world!\n')
buffer.getvalue() # 'hello, world!\n'
檔案模式(文字與二進位制)現在確定通過讀取檔案(以及寫入所需的型別)生成的資料型別:
with open('data.txt') as f:
first_line = next(f)
assert type(first_line) is str
with open('data.bin', 'rb') as f:
first_kb = f.read(1024)
assert type(first_kb) is bytes
文字檔案的編碼預設為 locale.getpreferredencoding(False)
返回的任何內容。要明確指定編碼,請使用 encoding
關鍵字引數:
with open('old_japanese_poetry.txt', 'shift_jis') as text:
haiku = text.read()