set(iterable)

# 创建一个空集合
set1 = set()
print(set1)  # 输出 set()

# 创建一个包含元素的集合
set2 = set([1, 2, 3, 4, 5])
print(set2)  # 输出 {1, 2, 3, 4, 5}

# 创建一个包含重复元素的集合
set3 = set([1, 2, 2, 3, 3, 3])
print(set3)  # 输出 {1, 2, 3}

# 创建一个包含字符串的集合
set4 = set("hello")
print(set4)  # 输出 {'l', 'o', 'e', 'h'}

set1 = set([1, 2, 3])
set1.add(4)
print(set1)  # 输出 {1, 2, 3, 4}

set1.add(2)
print(set1)  # 输出 {1, 2, 3, 4}，元素2已经存在，不会重复添加

set1 = set([1, 2, 3, 4])
set1.remove(3)
print(set1)  # 输出 {1, 2, 4}

set1.remove(5)  # 删除不存在的元素5，引发KeyError异常

set1 = set([1, 2, 3, 4])

if 3 in set1:
    print("元素3存在于集合中")
else:
    print("元素3不存在于集合中")

set1 = set([1, 2, 3])
set2 = set([3, 4, 5])

# 并集
union_set = set1 | set2
print(union_set)  # 输出 {1, 2, 3, 4, 5}

# 交集
intersection_set = set1 & set2
print(intersection_set)  # 输出 {3}

# 差集
difference_set = set1 - set2
print(difference_set)  # 输出 {1, 2}

set1 = set([1, 2, 3, 4, 5])
print(len(set1))  # 输出 5

set1 = set([1, 2, 3])
set1.clear()
print(set1)  # 输出 set()

set1 = set([1, 2, 3])
set2 = set1.copy()
print(set2)  # 输出 {1, 2, 3}

set1 = set()
if not set1:
    print("集合为空")