range() vs xrange() in Python

In Python 2, range() and xrange() were both used to generate sequences of numbers, but they worked differently:

1. range():
   • In Python 2, range() returned a list of numbers. For example, range(5) would return [0, 1, 2, 3, 4].
   • It generated the entire list in memory, which could be inefficient if the range is large.
2. xrange():
   • xrange() in Python 2 returned an iterator, not a list. This means it didn’t generate the entire sequence at once, but instead generated each number in the sequence on demand (lazily).
   • This made xrange() more memory-efficient for large ranges.

In Python 3:

• xrange() was removed and the range() function was changed to behave like xrange() did in Python 2.
• So, in Python 3, range() is now an iterator and is much more memory-efficient compared to the Python 2 range(), because it doesn’t generate a full list in memory.

Key differences:

• Python 2:
  • range() → returns a list
  • xrange() → returns an iterator
• Python 3:
  • range() → behaves like xrange() from Python 2 (returns an iterator)

In short: If you’re using Python 3, just use range(). If you’re on Python 2, use xrange() when you want better memory efficiency.