How do I read (or write) binary data in Python?

Python Programming Server Side Programming

To read or write a binary file, at first you need to understand the different file modes for Binary Files in Python −

Mode	Description
rb	Opens a file for reading only in binary format. The file pointer is placed at the beginning of the file. This is the default mode.
rb+	Opens a file for both reading and writing in binary format. The file pointer placed at the beginning of the file.
wb	Opens a file for writing only in binary format. Overwrites the file if the file exists. If the file does not exist, creates a new file for writing.
wb+	Opens a file for both writing and reading in binary format. Overwrites the existing file if the file exists. If the file does not exist, creates a new file for reading and writing.
ab	Opens a file for appending in binary format. The file pointer is at the end of the file if the file exists. That is, the file is in the append mode. If the file does not exist, it creates a new file for writing.
ab+	Opens a file for both appending and reading in binary format. The file pointer is at the end of the file if the file exists. The file opens in the append mode. If the file does not exist, it creates a new file for reading and writing.

Read a Binary File

Let’s say we have a binary file. We can read it using the read() method. First, we will open the Binary File using the rb mode of the open() method. We have the following source file in D: drive −

Example

Let’s see the complete code

# Open a binary file
f = open('D:\PythonLogo.png', 'rb')

# Read lines
data = f.read()

# Display the data
print(data)

Output

The Binary Files are not huma-readable and the content is unrecognizable. The actual output was bigger. We have shown only some part below.

b'\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR\x00\x00\x04\xb0\x00\x00\x04\xb0\x08\x06\x00\x00\x00
\xeb!\xb3\xcf\x00\x00\x00\x04gAMA\x00\x00\xb1\x8f\x0b\xfca\x05\x00\x00\x00
cHRM\x00\x00z&\x00\x00\x80\x84\x00\x00\xfa\x00\x00\x00\x80\xe8\x00\x00u0\x00\x00\xea`\x0
0\x00:\x98\x00\x00\x17p\x9c\xbaQ<\x00\x00\x00\x06bKGD\x00\xff\x00\xff\x00\xff\xa0\xbd\xa7\x
93\x00\x00\x00\x07tIME\x07\xe1\x08\n\x07\x16\x07\xc9\xb2\xff\xd3\x00\x00\x80\x00IDATx\xda\
xec\x9dw\xbc]e\x95\xf7\x7f\xcf>\xe7\xa6\x91@\xe8\xc5\x02\xa2\x88\x14q0B\x12\xc0\x99\x00!\x
88(\x02\x9a\x8c\x85"\xea\x80b\xc5\x02\xa1\xf8z\xa78\x8aJ\x13EeF\x1d\xdb\x94\x80@\x08\xea\x
a0\x8c\xe0\x0c\x98\x10`\x94\x92\xd0D@,#\x88\xd4\x90r\xef\xd9\xeb\xfd#\x01\x02i\xe7\x9e\xb3
\xcb\xf3\xac\xfd\xfd~>\xef;
.
.
.
\xcdn\xd2d\xb1Q\xdf\xfa\xe9\x8d|\x8f\x14\x00\x00\x00\xb4\t\x02\x0b\x00\x00\x00\xe0Q\x98\xa
9\xd0\xd5\xc7\x1c$Izp\xee>\x9a\xd8\xfa\x98\x1d\xffdr\x7f\x153\x8f\xfa\xf8\xa3\xcdQJ\x07\xec\x
e5\xc8\xf5X\x95\x96\x1eu\n\xdb\xac\xa4-
{\xf9{\xdbe\xf6\xc0#\xfe\xa7\t\xdd\xaf\xed\x9a\xd9\xd1\xf5\xe4\x83\xdawf\xc7w>m\xdb\xbc5-
X\xff
\xb3\x07\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xd02\xff?\xca\x9f\x86X\x17m\x83=\
x00\x00\x00%tEXtdate:create\x002017-08-
10T07:22:07+00:00u\xea\xe6c\x00\x00\x00%tEXtdate:modify\x002017-08-
10T07:22:07+00:00\x04\xb7^\xdf\x00\x00\x00\x00IEND\xaeB`\x82'

Write to a Binary File

The wb mode of the open() method is used to open a file in format form writing.

Note − The Binary Files are not huma-readable and the content is unrecognizable

Let’s see the complete example. Here, the file will get stored in E drive with the name

Example

MyDemoBinary.bin −

# Open a file in binary format for writing
f = open("E:\MyDemoBinary.bin","wb")

# Elements to be added to the binary file
a = [100, 200, 300]

# Convert the integer elements to a bytearray
myArr = bytearray(a)

# The byte representation ius now written to the file
f.write(myArr)
f.close()