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This article introduces the relevant knowledge of "why Python does not support iTunes + self-increasing grammar". In the operation of actual cases, many people will encounter this dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

1. The integer of Python is immutable.

When we define I = 1000, different languages will handle it differently:

Languages such as C (pronounced int I = 1000) apply for a piece of memory space and "bind" it with a fixed name I while writing a variable value of 1000. Here, the address and type of I are fixed, while the value is variable (within a certain range of representation).

Python (I = 1000) also applies for a piece of memory space, but it "binds" to the number 1000, that is, the address and type of 1000 is fixed (immutable). As for I, it is just a name label affixed to 1000 and does not have a fixed address and type of its own.

So when we "i=i+1" I, they are treated differently:

Languages such as C first find the value stored in the address of I, and then add it to 1. After the operation, the new value replaces the old value.

The operation of Python is to add 1 to the number I points to, then bind the result to a newly applied memory space, and then "paste" the name label I to the new number. New and old numbers can exist at the same time, not a replacement relationship.

To make an inappropriate analogy: the I in C is like a host, the number 1000 is parasitic on it, while the 1000 in Python is like a host, the name I parasites on it. I in C and 1000 in Python, they are parasitic on the underlying memory space.

It can also be understood like this: the variable I in C is a first-class citizen, and the number 1000 is a variable attribute of it; the number 1000 in Python is a first-class citizen, and the name I is a variable attribute of it.

With the above groundwork, let's take a look at iTunes, and it is not difficult to find:

In languages such as C, iTunes + can indicate an increase in the numerical attribute of I, which does not open up new memory space or produce new first-class citizens.

In languages such as Python, iTunes + is meaningless if it is an operation on its name attribute (you can't change I to j in alphabetical order) If it is understood as the operation of the digital ontology, then the situation will become complicated: it will produce a new first-class citizen 1001, so it needs to be assigned a memory address, and if it takes up 1000 of the address, it will involve the recycling of old objects. then the original reference relationship for 1000 will be affected, so we can only open up new memory space for 1001.

If Python supports iTunes, its operation is more complex than C's iTunes +, and its meaning is no longer "increase the number by 1" (self-increment), but "create a new number" (add), so the "self-increment operator" (increment operator) does not live up to its name.

Python can theoretically implement the iTunes + operation, but it must redefine the "self-increment operator" and cause misunderstanding to people with experience in other languages, so let's just write it as I + = 1 or I = I + 1.

2. Python has iterated objects

The main purpose of designing iTunes structures is to facilitate the use of three-segment for structure:

For (int I = 0; I < 100; iTunes +) {/ / execute xxx}

This kind of program is concerned with the self-increasing process of the number itself, and the addition of the number is associated with the execution of the program body.

There is no way to write this for structure in Python, it provides a more elegant way:

For i in range: # execute xxx my_list = ["Hello", "I'm Python Cat", "Welcome to follow"] for info in my_list: print (info)

This reflects a different way of thinking, it is concerned with iterative traversal within a numerical range, and does not care about and does not need to artificially add numbers.

The iterable object / iterator / generator in Python provides a very good iteration / traversal usage, providing a complete replacement for iTunes +.

For example, the above example implements traversing the values in the list, and Python can also use enumerate () to traverse both the subscript and the specific value:

My_list = ["Hello", "I am Python cat", "Welcome to follow"] for I, info in enumerate (my_list): print (I, info) # print result: 0 Hello 1 I am Python cat 2 welcome to follow

For example, for dictionary traversal, Python provides keys (), values (), items () and other traversal methods, which are very useful:

My_dict = {'averse:' 1percent, 'breadth:' 2percent, 'clockwise:' 3'} for key in my_dict.keys (): print (key) for key, value in my_dict.items (): print (key, value)

With such a sharp weapon, where is the opportunity for iTunes + to give full play to its talents?

Not only that, I + = 1 or I = I + 1 is rarely used in Python. Because there are iterable objects that can be seen everywhere, developers can easily operate on a range of values, so there are few demands for adding up to a certain value.

So, going back to our initial question, in fact, these two "self-increment" writing methods are not much better than iTunes +, just because they are general-purpose operations and do not need to introduce new operators, so Python continues a basic support. The real winners are actually a variety of iterable objects!

This is the end of the introduction of "Why Python does not support iTunes + self-increasing grammar". Thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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