# =================  声明变量   =================
print("=================  声明变量   =================")
'''
    所有变量都是对象，引用类型
'''
# 方式一，自动类型 
a = 1 # 变量
print(a)
# 方式一，指定类型
b:str = "1" #变量
c:str = 1 # 运行没问题，编译器会提示。c
print(b)


# =================  数据类型   =================
print("=================  数据类型   =================")
'''
文本类型：   str
数值类型：   int, float, complex
序列类型：   list, tuple, range
映射类型：   dict
集合类型：   set, frozenset
布尔类型：   bool
二进制类型：  bytes, bytearray, memoryview
'''

xStr = "Hello World" #  str
print(xStr)
print(type(xStr))

xInt = 29   # int
print(xInt)
print(type(xInt))

xFloat = 29.5   # float 
print(xFloat)
print(type(xFloat))

xComplex = 1j   # complex   
print(xComplex)
print(type(xComplex))

xList = ["apple", "banana", "cherry"]   # list  
print(xList)
print(type(xList))

xTuple = ("apple", "banana", "cherry")  # tuple 
print(xTuple)
print(type(xTuple))

xRange = range(6)   # range 
print(xRange)
print(type(xRange))

xDict = {"name" : "Bill", "age" : 63}   # dict  
print(xDict)
print(type(xDict))

xSet = {"apple", "banana", "cherry"}    # set   
print(xSet)
print(type(xSet))

xFrozenset = frozenset({"apple", "banana", "cherry"})   # frozenset 
print(xFrozenset)
print(type(xFrozenset))

xTrue = True    # bool  
print(xTrue)
print(type(xTrue))

xFalse = False  # bool  
print(xFalse)
print(type(xFalse))

xNone = None    # NoneType  
print(xNone)
print(type(xNone))


xBytes = b"Hello"   # bytes 
print(xBytes)
print(type(xBytes))

xByteArray = bytearray(5)   # bytearray 
print(xByteArray)
print(type(xByteArray))

xMemoryView = memoryview(bytes(5))  # memoryview    
print(xMemoryView)
print(type(xMemoryView))

# =================  类型转换   =================
print("=================  类型转换   =================")
'''
使用构造函数完成在 python 中的转换：
    int() - 用整数字面量、浮点字面量构造整数（通过对数进行下舍入），或者用表示完整数字的字符串字面量
    float() - 用整数字面量、浮点字面量，或字符串字面量构造浮点数（提供表示浮点数或整数的字符串）
    str() - 用各种数据类型构造字符串，包括字符串，整数字面量和浮点字面量
'''

castIntX = int(1)   # x 将是 1    
print(castIntX)
print(type(castIntX))

castIntY = int(2.5) # y 将是 2    
print(castIntY)
print(type(castIntY))

castIntZ = int("3") # z 将是 3    
print(castIntZ)
print(type(castIntZ))

castFloatX = float(1)     # x 将是 1.0
print(castFloatX)
print(type(castFloatX))

castFloatY = float(2.5)   # y 将是 2.5
print(castFloatY)
print(type(castFloatY))

castFloatZ = float("3")   # z 将是 3.0
print(castFloatZ)
print(type(castFloatZ))

castFloatW = float("4.6")# w 将是 4.6
print(castFloatW)
print(type(castFloatW))

castStrX = str("S2") # x 将是 'S2'
print(castStrX)
print(type(castStrX))

castStrY = str(3)    # y 将是 '3'
print(castStrY)
print(type(castStrY))

castStrZ = str(4.0)  # z 将是 '4.0'
print(castStrZ)
print(type(castStrZ))