Why Does Iteratively Removing Items from a Python List Produce Unexpected Results?

Strange Behavior When Removing Items Iteratively in Python

In Python, strange results can occur when deleting items from a list during iteration. Consider the following code:

Expected output: [20, 21, ..., 49]

Actual output: [2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 21, ..., 49]

Reason:

The problem stems from modifying the list while iterating over it. During the first loop iteration, 1 is removed. However, the subsequent iteration no longer points to 2 in the shortened list but instead to 3. This continues until only elements greater than 20 remain.

Solutions:

• List Comprehension:

• In-place Alteration:

• Prior Processing with Generator Expression:

It's important to note that modifying a list's length during iteration is not generally recommended. The provided solutions offer alternative approaches to achieving the desired outcome.

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