python read（）函数读取多于指定的字符

Question

first_file.txt

“
Hello World
This is our new text file
and this is another line.
Why? Because we can.
“

结果连接到我，见下文。

with open('first_file.txt') as f:
    print(f.read(2))
    print(f.read(3))
    print(f.read(8))
    print(f.read(15))
    print(f.read()) 

谁能解释read（8）和read（15）？请参阅下面的输出。

He
llo
 World
T
his is our new 
text file
and this is another line.
Why? Because we can.

Answer 1

输出看起来很奇怪，因为它也在打印新行。如果计算它打印的字符数，则在考虑换行符时输出是正确的。

当你调用print()时，python会在输出中添加换行符。以下是每次调用print时python所看到的内容：

>>> f.read(2):  'He'+\n              <- 2 characters + newline
>>> f.read(3):  'llo'+\n             <- 3 characters + newline
>>> f.read(8):  ' World\nT'+\n       <- 8 characters + newline
>>> f.read(15): 'his is our new '+\n <- 15 characters + newline
>>> 
>>> f.read():   'text file\nand this is another line.\nWhy? Because we can.'+\n

当您对文件调用read时，它会将光标位置移动指定的字符数。当你再次打电话给它时，它会从它停止的地方回来。如果不指定数字，它将一直读到文件末尾。