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Introduction to the Python struct moduleThe struct module in Python is used to convert native Python data types such as strings and numbers into a string of bytes and vice versa. It is used mostly for handling binary data stored in files or from network connections, among other sources. Python struct is a built-in module, which means we don't need to manually install the struct module on our system. In this tutorial, we will learn about the python struct module. We will cover various functions that are available in this module, for example, Getting started with Python struct moduleThe Python struct module is used to provide a simple Pythonic interface to access and manipulate C’s structure datatype. This module can convert Python values to a C structure and vice-versa. The C structure is used as a Python bytes object since there is nothing called an object in C; only byte-sized data structures. The following table shows some of the notations that are used in C and Python to represent the data types. See the table below:
Python struct.pack() methodThe python struct.pack(format, value1, value2, …) Here Example of Python struct.pack() methodNow let us take an example and see how we can use the python
Output: <class 'bytes'>
b'\x01\x00\x00\x00\x02\x00\x00\x00\x03\x00\x00\x00' Notice that the type of packed variable is bytes. Now let us try to understand the code. As you can see in the above program, it stores the 3 integers 1, 2, and 3 in a byte
object using
Output: Notice that we use Python struct.unpack() methodThe struct.unpack(format, string) This is actually the reverse of Example of struct.unpack() methodNow, let us take an example and see how
Output: (1, 2, 3) Notice that the python
Output: Notice that we provide the format for char characters while the given string_bytes was of integers types that is why we get the above error. Python struct.calcsize() functionThe Python This function takes only on the argument, which is the format of the data type, and based on the argument, this function returns the size of the specified data types in bytes. Example of Python struct.calcsize() functionNow let us take an example and see how the python
Output: The size of an integer is : 4
The size of a char is : 1
The size of a float is : 4 Notice that the python
Output: The size of 3 integer is : 12
The size of 5 char is : 5
The total size is : 18 Notice that the size of three integer data types in total is 12 and we get the same output. Python struct.pack_into() functionThe struct.pack_into(Format, buffer, offset, value1, value2, …) In the above syntax, Format refers to the format specifier, as always. Example of struct.pack_into() functionNow let us take an example and see how the python struct.pack_into() function actually works. Before writing our program, we have to first import ctypes because this function uses the pack values which are available in the ctypes. See the example below:
Output: b'\x01\x00\x00\x00\x02\x00\x00\x00' Notice that in the above code, we first created a buffer size string and we get our packed values in the buffer string. If we will provide more format sizes or format specifiers than provided values, the program will return an error. See the example below:
Output: Notice that we only provided two values and gave format size for 5, so the program returns the above error. Python struct.unpack_form() functionIt is similar to python struct.unpack_from(Format, buffer, offset) This function returns a tuple of values, similar to the python Example of Python struct.unpack_form() functionNow let us take an example of python struct.unpack_form() method and see how it actually works in the python program. See the example below:
Output: (1, 2, 3) Notice that the python SummaryThe struct module in Python is used to convert native Python data types such as strings and numbers into a string of bytes and vice versa. In this tutorial, we learned about the Python struct module. We learned how we can find the size and convert different data types into bytes. At the same
time, we cover various functions that are available in this module including python We also discussed some of the common errors that can occur while using the python struct module and its various functions. To summarize, this tutorial contains all the necessary examples and functions that are needed in order to start working with the python struct module. Further ReadingPython struct module documentation Why struct is used in Python?The module struct is used to convert the native data types of Python into string of bytes and vice versa. We don't have to install it. It's a built-in module available in Python3. The struct module is related to the C languages.
Can we use struct in Python?This module performs conversions between Python values and C structs represented as Python bytes objects. Format strings are the mechanism used to specify the expected layout when packing and unpacking data. Module struct is available in Python 3.
What does struct unpack do Python?Python struct pack_into(), unpack_from()
These functions allow us to pack the values into string buffer and unpack from a string buffer. These functions are introduced in version 2.5.
How do you read a structure in Python?Reading binary data as a numpy array:. np. frombuffer(bytes_data, dtype=...) : Interpret the given binary data (e.g. a python bytes instance) as a numpy array of the given dtype. ... . np. fromfile(filename, dtype=...) : Read binary data from filename .. |