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This article mainly explains "what are the knowledge contents of Python". Friends who are interested may wish to have a look. The method introduced in this paper is simple, fast and practical. Next, let the editor take you to learn "what are the knowledge contents of Python"?

Ellipsis is also an object.

In Python, everything is an object,... No exception. In Python3... It's called Ellipsis.

> type (...)

But in python2 there is no... This grammar. You can only use Ellipsis directly to get:

> type (Ellipsis)

It is true when it is converted to a Boolean:

> bool (...) True

So this. What is the use in the end? it is said that it is the grammatical sugar of Numpy. People who do not use Numpy can be said to be useless.

Or you can use... Instead of pass, such as:

Def test (): pass# can be replaced with def test ():... The first letter of a class is not necessarily capitalized.

Under normal circumstances, the code we write seems to acquiesce to the rule that the first letter of the class name is capitalized, while the example is lowercase. But it's not mandatory, and it doesn't matter if you do the other way around.

But there are some built-in classes with lowercase initials and uppercase instances.

For example, bool is the class name, and True,False is its instance

For example, ellipsis is the class name and Ellipsis is the instance.

And a series of data types such as int,string,float,list,tuple,dict are class names, and they are all lowercase.

Incremental assignment has better performance.

Operators such as + = and * = are called incremental assignment operators.

Here we use + = as an example, the following two writing methods are equivalent in effect.

# the first a = 1; a + = the second a = 1; a = a + 1

+ = the magic method used behind it is _ _ iadd__,. If this method is not implemented, it will settle for second best and use _ _ add__.

What's the difference between the two ways of writing?

Using a list for example a + = b, using _ _ iadd__ is like using a.extend (b). If you use _ _ add__, it is a = astatb. The former extends directly on the original list, while the latter first takes the value from the original list, expands it in a new list, and then returns the new list object to the variable. Obviously, the latter consumes more.

So try to use incremental assignments when you can.

The order of values of and and or

And and or are two logical operators that we are all too familiar with. And we usually only use it to make judgments, and seldom use it to take values.

If all values in an or expression are true, Python selects the first value, while the and expression selects the second.

>

Normally, we execute the Python command under the terminal like this.

For i in range (3):... Print (I)... 12

Actually > and. These two prompts can also be modified:

> import sys > sys.ps1'> sys.ps2'>. Sys.ps2 ='. > > sys.ps1 = 'aaa > >' aaa > for i in range (3):. Print (I). 012 so far, I believe you have a deeper understanding of "what is the knowledge content of Python". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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