迭代字典中的整数键时出错"int object is not subscriptable“Python 3

my_dict = {1: 'one', 2: 'two', 3: 'three'}

for key in my_dict:
    print(key, my_dict[key])

my_dict = {1: 'one', 2: 'two', 3: 'three'}

for key, value in my_dict.items():
    print(key, value)

my_dict = {1: 'one', 2: 'two', 3: 'three'}

for key in my_dict:
    if isinstance(key, int):
        print(key, my_dict[key])

my_dict = {1: 'one', 2: 'two', 3: 'three'}

# 方法1：直接迭代字典
print("方法1：直接迭代字典")
for key in my_dict:
    print(key, my_dict[key])

# 方法2：使用items()方法
print("\n方法2：使用items()方法")
for key, value in my_dict.items():
    print(key, value)

# 方法3：检查键的类型
print("\n方法3：检查键的类型")
for key in my_dict:
    if isinstance(key, int):
        print(key, my_dict[key])