数据类型转换：Data_type_conversion

今日笔记：

# _author:VULCAN
# date:2018/8/21
# int--->str
# i = 1
# a = str(i)
# print(a, type(a))

# str--->int str转换为int时，str的数据得为数字
# x = "3678sdf"
# x1 = "1542"
# y = int(x1)
# print(x1, type(x1))

# str--->bool,只要是空字符串，转换后就是False,只要字符串是非空,转换后就是True
# x = "3678sdf"
# x1 = bool(x)
# y = ""
# y1 = bool(y)
# print(x1)  # True
# print(y1)

# bool--->str 只要是True，转换后就是非空字符串,只要是False,转换后就是空字符串
# d = True
# d1 = str(d)
# print(d1, type(d1))
# f = False
# f1 = str(f)
# print(f1, type(f1))

# int--->bool 遵循非零即True原则
# a = 0
# aa = 1
# aaa = 199
# a1 = bool(a)
# a2 = bool(aa)
# a3 = bool(aaa)
# print(a1)
# print(a2)
# print(a3)

# bool--->int True--->1 False--->0
# t = True
# t1 = int(t)
# print(t1)
# f = False
# f1 = int(f)
# print(f1)
# while True:# True 需要先转换为1,所以效率低
#     pass
# while 1:  # 效率高于while True
#     pass