1. What assembly language
a. machine language (binary directly communicate directly with computers directly access the hardware directly)
Pros: The computer can directly read, fast
Disadvantages: development efficiency is very low, difficult to remember, inconvenient to read and write
b. assembly language (expressed in simple English binary identifier, but also the hardware directly)
Pros: relatively high development efficiency machine language,
Cons: the efficiency is lower than machine language
c. high-level language (not directly recognized by the computer, it needs to be executed after conversion)
By way of converting them can be divided into:
Compiled: after a translation, you can run multiple times after holding the result of translation. More convenient, more efficient. If you need to modify the application once, you must modify the source code, then recompile to generate a new file (obj file) to perform, only the target file without the source code, modify inconvenient.
Advantages: high efficiency
Disadvantages: low efficiency of development
Interpreter (like simultaneous interpretation)
as prime minister met with Chinese and foreign reporters, like the conference, say one in Chinese, English translation sentence. Translation line by line.
Advantages: high development efficiency
disadvantages: low efficiency
From the point of view of learning difficulty machine language >>> >>> assembly language level language
from high-level language development efficiency point of view >>> >>> assembly language machine language
From a performance point of view assembler language machine language >>> >>> Advanced language
2. The first python program
Both operating program python manner
a interactive.
Advantages: the input content immediately a corresponding return result
Cons: Can not permanently stored data
b command line (in the form of files).
Advantages: You can permanently store data
Disadvantages: For the moment, run the file a little trouble
To run a file needed py:
. A python the interpreter code read from the hard disk memory
b py file written to a hard disk into memory.
C py interpreter interpret the contents of the file to read, can be interpreted as a computer. identification statement
PS: python interpreter in two steps in front of a plain text editor exactly the same, only the third step is not the same (a grammar is explained, is a text display)
3. Variables
a. What is a variable?
Variable is the amount of change in
amount: measure / record the state of things / features
change: State / features may vary
b Why should there be variable.?
Help you record keeping things in a certain state or features
. C defined variables
variables must be defined after the call (use), variable names without the quotation marks
d variable of the three elements.
1) .id (): returns the string of numbers this string of numbers can be directly understood as a memory address.
2) .type (): returns the type of data corresponding to the variable
3) .value (): value of the variable which points to the data memory
4. Constant
The amount will not change, there is no special syntax constants in python on behalf of the program is running, usually uppercase variable name as a constant (programmer convention)