Python新手：理解TypeError的十个实例

原创深藏阁楼爱情的钟 2025-03-09 01:51 38阅读 0赞

`TypeError`是Python中一种常见的运行时错误。它通常发生在尝试对某种类型的数据执行不兼容的操作时。以下是十个理解`TypeError`的实例：

1. **数字与字符串混合**:
   ```python
   num = 5
   str = "hello"
   print(num + str)  # TypeError: can only concatenate str (not "int") to str
   ```

2. **错误地将列表赋给字典**:
   ```python
   list_data = ['apple', 'banana', 'cherry']
   dict_data = {'fruit': list_data}  # TypeError: '<list>' object does not support item assignment

dict_data = {key: value for key, value in list_data.items()}  # Correct way to assign a list to a dictionary
   ```

3. **尝试对非数字类型进行数学运算**:
   ```python
   str_num = "12"
   float_num = 5.6

try_addition = str_num + float_num  # TypeError: can only concatenate str (not "int") to str
   ```

4. **混合使用序列（如列表和元组）**:
   ```python
   list_data = [1, 'apple', 3.14],  # Mixed use of sequence types

try_access_value = list_data[0][2]]  # TypeError: list indices must be integers or slices, not tuple
   ```

5. **错误地将字典的值赋给变量**:
   ```python
   dict_data = {'name': 'John', 'age': 30}

value_assignment = dict_data['name'] = "Jane"  # TypeError: assignment destination must be a sequence
   ```

6. **使用不兼容的类型进行比较**:
   ```python
   int_num = 5
   str_num = "10"

try_comparison = int_num > str_num  # TypeError: cannot compare types 'int' and 'str'
   ```

7. **使用`*`操作符将元组与列表混合**:
   ```python
   tuple_data = (1, 'apple', 3.14))
   list_data = [5, 'banana', 6.28]]

mixed_product = tuple_data * list_data  # TypeError: can only concatenate list (not "tuple")) to list
   ```

8. **尝试使用`**`操作符提取字典的值**（Python 3.7 及以后版本）**：
   ```python
   dict_data = {'name': 'John', 'age': 30}

extracted_value = dict_data ** 1  # TypeError: unsupported operand type(s) for **: 'dict' and 'int'
   ```

9. **错误地使用`+`操作符连接两个不同类型的对象**:
    ```python
    int_num = 5
    str_num = "10"

combined_type = int_num + str_num  # TypeError: can only concatenate str (not "int")) to str
    ```

10. **尝试使用列表推导式（List Comprehension）创建一个字典，其中的值是另一个字典中的键**:
    ```python
    dict_data = {'first_key': 'value1', 'second_key': 'value2'}  # Original dictionary

wrong_comprehension = {key: dict_data[key] for key in dict_data}  # Error: Wrong usage of list comprehension. Result is a set, not a dictionary.

correct_comprehension = {key: value for key, value in dict_data.items()}  # Correct way to create a dictionary with values from another dictionary

print(wrong_comprehension)  # Output: {'first_key': 'value1', 'second_key': 'value2'}}
    
这十个实例展示了在Python中如何错误地使用数据类型，导致`TypeError`。理解这些错误可以帮助你在编程时避免它们。