← Python

Strings – Slicing

A slice [start:stop] extracts a substring from position start up to but not including stop

Part of: Python Coding — Module 30, WA Computer Science ATAR Year 11 — Control Structures and Data Types — Module 15

Understanding Strings – Slicing in Python

What it does: Omitting start defaults to 0. Slices from index 0 up to (not including) 3. Step -1 traverses the string backwards — a quick way to reverse. Start at 0, stop before 3: P(0) y(1) t(2). [:2] starts from 0, stops before index 2: h(0) e(1). [3:] starts at index 3 and takes everything to the end: l(3) o(4). Step of 2: take index 0, 2, 4 = a, c, e. Step of -1 reverses the string. Start and stop at the same index — nothing in between.

Common mistakes: Use colon : for slicing, not comma. Step cannot be 0: causes ValueError.

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Free printable worksheet with full answer key — or add this module to a class and your students practise it interactively.

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This module's key terms are also in a printable crossword (Modules 21–30) and word search (Modules 21–40).

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Learning
Duo
What does 'Python'[0:3] return?
'Pyt''Pyth'
Matches
❌ 'hello'[1,4]
↓
Error: Use colon not comma
Applying
Meanings
Term
Slice
Meaning
Extract a portion of a string using [start:stop].
Practice
word = 'Python'
Testing
Gaps
print(word[:3])
Check Answer
Spots
1word = 'hello'
2part = word[0,3]

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Quick Questions

1. What does 'Python'[0:3] return?
A. 'Pyth'
B. 'Pyt' ✓
Start at 0, stop before 3: P(0) y(1) t(2)
2. What does 'hello'[:2] return?
A. 'he' ✓
B. 'hel'
[:2] starts from 0, stops before index 2: h(0) e(1)
3. What does 'hello'[3:] return?
A. 'llo'
B. 'lo' ✓
[3:] starts at index 3 and takes everything to the end: l(3) o(4)
4. Is the stop index included in a slice?
A. No it stops before it ✓
B. Yes
Same rule as range() — slicing stops BEFORE the stop index
5. What does 'abcdef'[::2] return?
A. 'ace' ✓
B. 'bdf'
Step of 2: take index 0, 2, 4 = a, c, e

Match the Pairs

'hello'[1,4] → Error: Use colon not comma
'hello'[10:20] → Invalid: But returns '' not error
'hello'[:3] → Valid: Returns 'hel'
'hello'[::-1] → Ok: Reverses the string
print('hello'[1:4]) → Output: ell
print('python'[2:]) → Output: thon

Key Term

Slice
Extract a portion of a string using [start:stop].~~[start:stop]

Fill in the Blanks

1. word = 'Python' print(word[0:3])
2. word = 'hello' print(word[:3])
3. word = 'hello' print(word[2:])
4. word = 'hello' print(word[::-1])
5. text = 'abcdef' print(text[1:5])

Spot the Error

Question 1
A word = 'hello'
B part = word[0,3]
C print('Slice:', part)
D print('Done')
Line B — Use colon : for slicing, not comma
Question 2
A word = 'hello'
B part = word[1:4:0]
C print('Slice:', part)
D print('Done')
Line B — Step cannot be 0: causes ValueError
Question 3
A word = 'hello'
B part = word(1:3)
C print('Slice:', part)
D print('Done')
Line B — Use square brackets [] for slicing, not parentheses ()
Question 4
A word = 'hello'
B part = word[0:5:]
C print('Slice:', part)
D # trying to get all
Line B — Trailing colon without step is fine but unnecessary: remove it for clarity
Question 5
A part = 'hello'[-1:-4]
B word = 'hello'
C print('Slice:', part)
D print('Done')
Line A — Start must be before stop: -4 comes before -1 in the string

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