How do you write bytes in python?

Files are used in order to store data permanently. File handling is performing various operations (read, write, delete, update, etc.) on these files. In Python, file handling process takes place in the following steps:

1. Open file
2. Perform operation
3. Close file

There are four basic modes in which a file can be opened― read, write, append, and exclusive creations. In addition, Python allows you to specify two modes in which a file can be handled― binary and text. Binary mode is used for handling all kinds of non-text data like image files and executable files.

Write Bytes to File in Python

Example 1: Open a file in binary write mode and then specify the contents to write in the form of bytes. Next, use the write function to write the byte contents to a binary file. 

Python3

some_bytes = b'\xC3\xA9'

with open("my_file.txt", "wb") as binary_file:

    binary_file.write(some_bytes)

Output:

my_file.txt

Example 2: This method requires you to perform error handling yourself, that is, ensure that the file is always closed, even if there is an error during writing. So, using the “with” statementis better in this regard as it will automatically close the file when the block ends.

Python3

some_bytes = b'\x21'

binary_file = open("my_file.txt", "wb")

binary_file.write(some_bytes)

binary_file.close()

Output:

my_file.txt

Example 3: Also, some_bytes can be in the form of bytearray which is mutable, or bytes object which is immutable as shown below.

Python3

byte_arr = [65,66,67,68]

some_bytes = bytearray(byte_arr)

some_bytes.append(33)

immutable_bytes = bytes(some_bytes)

with open("my_file.txt", "wb") as binary_file:

    binary_file.write(immutable_bytes)

Output:

my_file.txt

Example 4: Using the BytesIO module to write bytes to File

Python3

from io import BytesIO

write_byte = BytesIO(b"\xc3\x80")

with open("test.bin", "wb") as f:

    f.write(write_byte.getbuffer())

Output:

test.bin

I have a function that returns a string. The string contains carriage returns and newlines (0x0D, 0x0A). However when I write to a file it contains only the new line feeds. Is there a way to get the output to include the carriage return and the newline?

msg = function(arg1, arg2, arg3)
f = open('/tmp/output', 'w')
f.write(msg)
f.close()

martineau

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asked Aug 23, 2012 at 13:19

Blackninja543Blackninja543

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1

If you want to write bytes then you should open the file in binary mode.

f = open('/tmp/output', 'wb')

answered Aug 23, 2012 at 13:22

7

Write bytes and Create the file if not exists:

f = open('./put/your/path/here.png', 'wb')
f.write(data)
f.close()

wb means open the file in write binary mode.

answered Aug 4, 2020 at 12:41

2

Here is just a "cleaner" version with with :

with open(filename, 'wb') as f: 
    f.write(filebytes)

answered Nov 29, 2021 at 15:40

1

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