StringIO 与二进制文件？

发布于 2024-12-06 14:02:59 字数 197 浏览 1 评论 0原文

我似乎得到了不同的输出：

from StringIO import *

file = open('1.bmp', 'r')

print file.read(), '\n'
print StringIO(file.read()).getvalue()

为什么？是不是因为StringIO只支持文本字符串什么的？

原文

I seem to get different outputs:

from StringIO import *

file = open('1.bmp', 'r')

print file.read(), '\n'
print StringIO(file.read()).getvalue()

Why? Is it because StringIO only supports text strings or something?

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花落人断肠 2024-12-13 14:02:59

当您调用file.read()时，它会将整个文件读入内存。然后，如果您在同一个文件对象上再次调用 file.read() ，它已经到达文件末尾，因此它只会返回一个空字符串。

相反，请尝试重新打开文件：

from StringIO import *

file = open('1.bmp', 'r')
print file.read(), '\n'
file.close()

file2 = open('1.bmp', 'r')
print StringIO(file2.read()).getvalue()
file2.close()

您还可以使用 with 语句使代码更清晰：

from StringIO import *

with open('1.bmp', 'r') as file:
    print file.read(), '\n'

with open('1.bmp', 'r') as file2:
    print StringIO(file2.read()).getvalue()

顺便说一句，我建议以二进制模式打开二进制文件： open('1. bmp', 'rb')

When you call file.read(), it will read the entire file into memory. Then, if you call file.read() again on the same file object, it will already have reached the end of the file, so it will only return an empty string.

Instead, try e.g. reopening the file:

from StringIO import *

file = open('1.bmp', 'r')
print file.read(), '\n'
file.close()

file2 = open('1.bmp', 'r')
print StringIO(file2.read()).getvalue()
file2.close()

You can also use the with statement to make that code cleaner:

from StringIO import *

with open('1.bmp', 'r') as file:
    print file.read(), '\n'

with open('1.bmp', 'r') as file2:
    print StringIO(file2.read()).getvalue()

As an aside, I would recommend opening binary files in binary mode: open('1.bmp', 'rb')

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