如何将单个值加到单个字典项中？

# 示例字典
my_dict = {'key1': 10, 'key2': 20}

# 要添加的值
value_to_add = 5

# 要更新的字典键
key_to_update = 'key1'

# 更新字典项
my_dict[key_to_update] += value_to_add

print(my_dict)  # 输出: {'key1': 15, 'key2': 20}

from collections import defaultdict

# 示例字典
my_dict = defaultdict(int, {'key1': 10, 'key2': 20})

# 要添加的值
value_to_add = 5

# 要更新的字典键
key_to_update = 'key1'

# 更新字典项
my_dict[key_to_update] += value_to_add

print(dict(my_dict))  # 输出: {'key1': 15, 'key2': 20}

# 示例字典
my_dict = {'key1': 10, 'key2': 20}

# 要添加的值
value_to_add = 5

# 要更新的字典键
key_to_update = 'key1'

# 更新字典项
my_dict[key_to_update] = my_dict.get(key_to_update, 0) + value_to_add

print(my_dict)  # 输出: {'key1': 15, 'key2': 20}

cart = {'item1': 2, 'item2': 1}
item_to_update = 'item1'
quantity_to_add = 3

cart[item_to_update] += quantity_to_add
print(cart)  # 输出: {'item1': 5, 'item2': 1}

my_dict = {'key1': 10}
value_to_add = '5'  # 这是一个字符串

# 这将引发TypeError
my_dict['key1'] += value_to_add

my_dict['key1'] += int(value_to_add)