如何修復 Python 中的'TypeError: \'NoneType\' Object Iteration\”錯誤？

Handling 'NoneType' Object Iteration Error

When attempting to iterate over an iterable, such as a list or dictionary, a TypeError like "TypeError: 'NoneType' object is not iterable" occurs if the value assigned to the iterable is None. This error indicates that the object being iterated over is not iterable.

For example, consider the following code snippet:

<code class="python">data = None
for row in data:  # Raises TypeError
    print(row)</code>

Here, data is set to None, which is a special value in Python indicating the absence of a value. When the for loop tries to iterate over data, it encounters the TypeError because None is not iterable.

To resolve this issue, ensure that the value assigned to the iterable is a valid iterable object, such as a list or dictionary. Additionally, you can check if the value is None before attempting to iterate over it:

<code class="python">if data is not None:
    for row in data:
        print(row)</code>

Alternatively, you can handle the TypeError explicitly using a try/except block:

<code class="python">try:
    for row in data:
        print(row)
except TypeError:
    pass  # Handle the error here, e.g., print a message</code>

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