Python String Slicing: Start, Stop, and Step

This guide explains String Slicing: Start, Stop, and Step through a focused example and practical reasoning. No prior knowledge of this specific operation is required.

Understanding the Concept

A string slice text[start:stop:step] returns a new substring; stop is excluded. Omitted bounds use appropriate defaults, and a negative step can traverse backward.

When You Would Use This

Extract the prefix, suffix and reverse of an order code.

Step-by-Step Example

order_code = "INV-2026"
print(order_code[:3])
print(order_code[4:])
print(order_code[::-1])

How the Example Works

The first slice is INV, the second is 2026, and the final slice reverses every code point. Slices tolerate many out-of-range bounds without an IndexError.

Example Output

INV
2026
6202-VNI

Try It Yourself

Extract only the final four characters of "REF-1048".

Common Beginner Mistakes

Assuming the stop index is included.
Confusing text[4] with text[4:].
Expecting reversed code-point order to preserve complex grapheme clusters.

Key Takeaways

A string slice text[start:stop:step] returns a new substring; stop is excluded.
The first slice is INV, the second is 2026, and the final slice reverses every code point.
Avoid this mistake: Assuming the stop index is included.