官方文档：A Python program is constructed from code blocks. A block is a piece of Python program text that is executed as a unit. The following are blocks: a module, a function body, and a class definition. Each command typed interactively is a block. A script file (a file given as standard input to the interpreter or specified as a command line argument to the interpreter) is a code block. A script command (a command specified on the interpreter command line with the ‘-c‘ option) is a code block. The string argument passed to the built-in functions eval() and exec() is a code block. A code block is executed in an execution frame. A frame contains some administrative information (used for debugging) and determines where and how execution continues after the code block’s execution has completed.

s = "hello"
print(id(s)) # 2305859175064

a = 100
b = 100
print(a is b)  # True
print(a == b)  # True

a = 1000
b = 1000print(a == b) # True
print(a is b) # False 在command命令下为False, 在.py文件中（例如pycharm中）得到的结果为True。（详情见下面）

官方文档：The current implementation keeps an array of integer objects for all integers between -5 and 256, when you create an int in that range you actually just get back a reference to the existing object. So it should be possible to change the value of 1. I suspect the behavior of Python in this case is undefined.

Incomputer science, string interning is a method of storing only onecopy of each distinct string value, which must be immutable. Interning strings makes some stringprocessing tasks more time- or space-efficient at the cost of requiring moretime when the string is created or interned. The distinct values are stored ina string intern pool. –引⾃自维基百科

a = 1000
b = 1000print(id(a)) # 2135225709680
print(id(b)) # 2135225709680
print(a is b)  # True  .py文件运行

a = 1000
b = 10*100print(id(a)) # 1925536396400
print(id(b)) # 1925536643952
print(a is b) # False  .py文件运行

a = 5*5
b = 25print(id(a))  # 1592487712
print(id(b))  # 1592487712print(a is b)  # True  .py文件运行

a = "Incomputer science, string interning is a method of storing only onecopy of each distinct string value"
b = "Incomputer science, string interning is a method of storing only onecopy of each distinct string value"print(id(a)) # 2926961023256
print(id(b)) # 2926961023256print(a is b) # True  .py文件运行

# _*_ encoding:utf-8 _*_

a = "hello"
b = "中"print(a.encode("utf-8"))  # b'hello'
print(b.encode("utf-8"))  # b'\xe4\xb8\xad'
print(b.encode("gbk"))  # b'\xd6\xd0'

a = "编码"
print(a.encode("utf-8")) # b'\xe7\xbc\x96\xe7\xa0\x81'b = b'\xe7\xbc\x96\xe7\xa0\x81'
print(b.decode("utf-8"))  # 编码

# GBK 转换成 UTF-8
s = "我是文字"
bs = s.encode("gbk")# 把GBK转换成unicode，也就是解码
s = bs.decode("gbk")# 重新编码成UTF-8
bss = s.encode("utf-8")print(bss)