Today, learning content classification programming language, installation and set environment variables Python interpreter, two operating methods and variables Python program file execution step Python, the concept of constant, what they learn is still relatively simple.
First, the classification of programming languages
1.1, machine language
Binary programming instructions, hardware essentially direct operation
Advantages: high efficiency
Disadvantages: the development of low efficiency, high learning curve
1.2, assembly language
Instead of two labels made of instructions in English, but also the nature of the hardware directly
Advantages: high efficiency
Disadvantages: the development of low efficiency, high learning curve
1.3, high-level language
Must be translated into machine language the computer to perform
1.3.1, compiled
Compiled once, to get the results can be performed repeatedly without recompilation
Advantages: high efficiency
Disadvantages: trouble debugger, cross-platform poor
1.3.2, interpreted
Translate and execute
Advantages: development of high efficiency, high cross-platform, easy debugging
Disadvantages: low efficiency
Two, Python interpreter environment variable installation and
Three ways both run Python programs
3.1, Interactive
3.2, the command line
Step four executed, Python file
The Python interpreter code read from the hard disk into memory
Py file will be read from the hard disk into memory
Py interpreter read the contents of the file, interpreted into machine language
Fifth, the concept of variables and constants
5.1 Variable
5.1.1, the variable three elements:
Variable name: represents the memory address space, comparison is.
Data Type: decision-access modes exist in memory
Value: Data stored in the memory, the comparative ==
5.1.2, a small integer pool
In order to optimize the operation speed, Python is a number between [-5,256] open a separate memory,
When referring to them as data variables point to the same memory address.
5.1.3 garbage collection
Reference count: references to the objects the counter is 0, automatically reclaims the memory
Clear mark: problem solving circular references
Generational Recovery: Depending on the median survival time is divided into different levels, the lower, the higher the level garbage collection sweep frequency
5.2 Constant
python in no way specifically defined constants, usually expressed in uppercase variable names.