5、类型转换

my_str = "I love Python"
my_list = ["python", "java", "lanuage", "age", 'java']
my_list2 = [24, 12, 2.3, 9.7]
my_tuple = ("python", 33, "java", 8.8)
my_dict = {"name": "linda", "age": 88}
my_list1 = ['a', 'a', 1, 1, 2, 3]
my_set = {1, 2, 3}
print(my_list.count("java"))
a = 10
print(type(a))

a1 = str(a)  # 强制转换从int到str
print(type(a1))
print(type(int(a1)))        # str 转 int
print(tuple(my_list))       # list与tuple元组转换
print(list(my_tuple))
print(set(my_list1))        # 列表转成set变成不重复的
print(set(my_dict))         # 字典类型转成set只有key值
print(list(my_dict.values()))       # 字典转成列表，key,value可以单转
print(list(my_dict))
my_tuple1 = ('one', 1), ('two', 2), ('three', 3)
my_list_tuple = [('one', 1), ('two', 2), ('three', 3)]
print(my_tuple1)
print(type(my_list_tuple))
print(dict(my_list_tuple))


# 将对象 x 转换字符串

b = {"name": "linda", "age": 18}
str_b = repr(b)
print(str_b[0:3])

# 用来计算在字符串中的有效Python表达式,并返回一个对象
a = "[1,2,3]"
list_a = eval(a)
print(list_a[0])
b = '3*5'
print(eval(b))

print(chr(97))

ss = '《入海》，毛不易'
print(ss[1:3] + ss[-4:])