What are an expressions used in python?

[Atsushi]

I am recently started leaning about the Python programming language, so I am not having much idea about it. I know that it is a language that is experiencing more and more support for its cleanliness and straightforwardness in the world of Linux programming. That's why I chose this language for further studies. I want to complete my basic knowledge anyhow before trying some classes or institutes for deep studies. I have already got an enough idea from Python Commands. Thanks for providing all such information. Now please provide some details about the expressions that are used in python.

[X-Ray]

Python is a language known as mandatory, which means that the implementation consists of a series of commands that are executed one after another. Each command changes the variables, which represent the memory of implementation, or we normally say, "status" of the program. We can therefore distinguish between expressions that perform simple calculations, and commands that process a sequence of operations. The expressions are important because they manipulate the data structures of language. This distinguishes the concept of data structure programming languages in a more powerful syntax. While sometimes a language is characterized by the peculiarities of the syntax, in fact, what really makes the difference are the data structures manipulated by the expression of language. For example, Java and C + + are quite similar to the syntactic point of view, but just observe the data structure to realize that this is very different languages. In this sense, Python is closer to Java over C + +, although with a somewhat different syntax.

[Mecurtis]

In order to experiment programming, you must have the ability to execute expressions. Fortunately, Python has an interactive mode that enables you to experience directly the expressions that gradually write. Launching an interpreter, which can be both Linux and Windows, we get the following message (subject to change depending on the system and version):

Python 2.2.3 (# 1, Dec 12 2010, 10:30:38)
[GCC 2.95.3 20010315 (release)] on linux2
Type "help", "copyright", "credits" or "license" for more information.

We can then directly enter the expressions such as 2 +2 and see the results, using python as a desktop computer. Of course, once developed a program, you want to distribute to users. We have much to say yet to get around this problem, but it seems only right to mention what are the methods of distribution programs, which depend on operating systems.

[Timothi]

In the UNIX environment is sufficient to write a script and then use the classical syntax # / usr / bin / python. Placing it at the beginning of a file that contains a program in Python, and setting the x bit, the file that contains it becomes executable. With Windows you can not do the same, but there is an interesting program that lets you alter a program in python in a stand-alone executable. Council of the utility search on the Internet "py2exe" to learn more. You are now just starting with this language. There are many options, from using a simple text editor such as Notepad or vi, to idle as a development environment that is already included in the standard distribution of Python, to sophisticated commercial development environments, these can be easily found on the Internet as www.python.org the official site. However, to prove the most example we do on this course, simply a text editor and python interpreter, you can download (for free) directly from the site www.python.org.

[StudyBoy]

I would like to discuss about Numbers that are used in Python. We launch the python interpreter, and see ">>>". The prefix ">>>" is the "prompt", the message from the interpreter to say that it is ready to accept commands. Display it to distinguish what we write answers on what the interpreter. Then:

2 +2
4

Nothing strange, but we have found that using python syntax arithmetic traditional so-called "stuck". With another programming language, we could have 2 + 2 (forth, postfix) or (2 + 2) (lisp, code). It is important to note that the calculation results we can assign to a variable:

X = 2 +2
  X
 4

Note that in the first case the assignment has not printed anything. In reality, each operation returns something. The return value is the special value None, the interpreter simply does not print. Evaluating a variable instead we get a true value that is printed. When using the interpreter as a calculator is worth remembering that the _ special variable contains the last value calculated. So it can be handy as a reminder of support similar to the calculator display.