Python — Reference

A good understanding of Python reference

In Python, a variable is not a label of value like you may think. Instead, a reference in python means a different name for a memory location that has been associated. This means an entity allocated with some memory will be referenced with a different name other than the actual name of the memory.

The processing of variables in Python is very different from other languages. Variables in Python have a special attribute: identity, that is, “identity identification”. This special property is also called “reference” in many places.

How do References Work in Python?

Let’s first take a look at one example: in languages ​​such as C++, variable declaration and assignment can be separated:

int a;
a = 343;

But in python, you must perform assignment operations when declaring python variables

a = 343

If you directly use a variable that does not exist, an error will occur, NameError: name ‘a’ is not defined

In Python, when a = 343 is executed, it first creates the object 343 in memory, and then let a point to it, which is the reference. Like in the following diagram: