变量

　　声明变量

# Author :yanpengtao
# _*_coding:utf-8_*_

name = "Yanpengtao"
print("My name is :", name)

C:\day1\venv\Scripts\python.exe G:/PythonStudy/S14/day1/var.py
My name is : Yanpengtao

　　

上述代码声明了一个变量，变量名为： name，变量name的值为："Yanpengtao"，并输出该变量为"Yanpengtao"

变量定义的规则：

• 变量名只能是 字母、数字或下划线的任意组合
• 变量名的第一个字符不能是数字
• 以下关键字不能声明为变量名
  ['and', 'as', 'assert', 'break', 'class', 'continue', 'def', 'del', 'elif', 'else', 'except', 'exec', 'finally', 'for', 'from', 'global', 'if', 'import', 'in', 'is', 'lambda', 'not', 'or', 'pass', 'print', 'raise', 'return', 'try', 'while', 'with', 'yield']

变量的赋值：

# Author :yanpengtao
# _*_coding:utf-8_*_

name = "Yanpengtao"
print("My name is :", name)
name2 = name
print("name is :", name, "name2 is :", name2)
name = "Fengjie"
print("name is :", name, "name2 is :", name2)

C:\day1\venv\Scripts\python.exe G:/PythonStudy/S14/day1/var.py
My name is : Yanpengtao
name is : Yanpengtao name2 is : Yanpengtao
name is : Fengjie name2 is : Yanpengtao

　　上面的代码先定义了name变量，赋值为“Yanpengtao”，然后将name赋值给name2，此时name和name2的值是相同的，再将name的值改变成“Fengjie”，此时输出name为“Yanpengtao”，而name仍然是"Yanpengtao"，那这是怎么回事呢，下面进行分析：