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Python - range() Function

📌 What You Will Learn
  • Define the range() function and the sequence it generates
  • Use the three forms range(stop), range(start, stop), and range(start, stop, step)
  • Apply the rules for start, stop, and step values
  • Create reverse sequences with a negative step
  • Identify when a range is empty

What Is range()?

The range() function generates a sequence of numbers.

It is commonly used with for loops.

Forms

  • range(stop)
  • range(start, stop)
  • range(start, stop, step)

Rules

  • Start value is included.
  • Stop value is excluded.
  • Default start is 0.
  • Default step is 1.

Examples

for i in range(5):
    print(i)

for i in range(1, 6):
    print(i)

for i in range(1, 11, 2):
    print(i)

Reverse and Empty Range

Use a negative step for reverse order.

for i in range(10, 0, -1):
    print(i)

If a valid sequence cannot be generated, the range is empty.

Common Uses

Use range() for counters, indexes, sums, and repeated sequences.

📝 Key Takeaways
  • range() generates a sequence of numbers
  • The start value is included and the stop value is excluded
  • The default start is 0 and the default step is 1
  • A negative step creates numbers in reverse order
  • If a valid sequence cannot be generated, the range is empty
  • range() is commonly used with for loops

🧠 Test Your Knowledge

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