What\'s the Difference in Negative Integer Division between Python 2 and Python 3?

Tricky Negative Integer Division in Python

While working on an application, the surprising result of integer division raised questions. When dividing 8 by -7, the result is -2, an integer value. To understand this phenomenon, let's delve into the intricacies of integer division.

Integer Division vs. True Division

Python 2 uses integer division, denoted by "/", which results in an integer quotient. When dividing negative integers, the quotient is rounded towards the more negative value (floor division). This means that 8/-7 is truncated to -2, even though the actual value is closer to -1.143.

Python 3 Revisited

To avoid this ambiguity, Python 3 introduced true division, which always results in a float value unless both operands are integers. This is consistent with mathematical division and eliminates the need to manually convert operands to floats. Therefore, 8/-7 in Python 3 would correctly evaluate to -1.143.

Integer Division in Python 3

If you still require integer division in Python 3, the // operator can be employed. Similar to integer division in Python 2, it rounds the quotient towards negative infinity.

Historical Context

The behavior of integer division in Python 2 was influenced by historical programming languages and is not reflective of mathematical norms. Python 3 addressed this issue by introducing true division, aligning with the expectations of most developers.

Additional Resources

For further insights on this topic, refer to the Python Enhancement Proposal 238 (PEP 238) on the subject of changing the division operator:

[PEP 238 -- Changing the Division Operator](https://www.python.org/dev/peps/pep-0238/)

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