Python Bytecode

Byte code represents a fixed set of instructions that represents all operations like arithmetic operations, comparison operations, memory related operations etc..

which run on any operating system and hardware. It means the byte instructions are system independent or platform independent. The size of each byte code instruction is 1 byte and hence they are called with the name byte code.

Bytecode Explanation

Lets consider below program for viewing its byte code

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#Python program to add two numbers  
a = b = 10 
#take two variables and store 10 in to them 
print("Sum=", (a+b)) #display their sum

We can type this program in a text editor like Notepad and then save it as 'first.py'. It means, the first.py file contains the source code

Now, let's compile the program using Python compiler as

C:\>python first.py

It will display the result as: sum=20

Bytecode 'dis' module

We do not want the output of the program. We want to see the byte code instructions that were created internally by the Python compiler before they are executed by the PVM.

For this purpose, we should specify the 'dis' module while using python command as:

C:\>python -m dis first.py

It will produce the following output:

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  1           0 LOAD_CONST               0 (10)
              2 DUP_TOP
              4 STORE_NAME               0 (a)
              6 STORE_NAME               1 (b)

  2           8 LOAD_NAME                2 (print)
             10 LOAD_CONST               1 ('Sum =')
             12 LOAD_NAME                0 (a)
             14 LOAD_NAME                1 (b)
             16 BINARY_ADD
             18 CALL_FUNCTION            2
             20 POP_TOP
             22 LOAD_CONST               2 (None)
             24 RETURN_VALUE