String slicing behavior in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of negative step slicing

What is the output of this Python code?

text = 'abcdefg'
result = text[5:2:-1]
print(result)

Python

text = 'abcdefg'
result = text[5:2:-1]
print(result)

A 'cde'

B 'def'

C 'fed'

D 'edc'

💡 Hint

Remember that slicing with a negative step goes backwards and excludes the stop index.

The slice text[5:2:-1] starts at index 5 ('f'), goes backwards up to but not including index 2 ('c'), so it includes indices 5,4,3 which are 'f','e','d'.

❓ Predict Output

intermediate

Slicing with omitted start and stop

What does this code print?

text = 'python'
result = text[::-2]
print(result)

Python

text = 'python'
result = text[::-2]
print(result)

A 'nhy'

B 'nohty'

C 'nhot'

D 'nht'

💡 Hint

When start and stop are omitted with a negative step, slicing goes from end to start.

text[::-2] means start from the end and take every second character backwards: indices 5('n'),3('h'),1('y').

❓ Predict Output

advanced

Effect of out-of-range indices in slicing

What is the output of this code?

text = 'hello world'
result = text[3:100]
print(result)

Python

text = 'hello world'
result = text[3:100]
print(result)

A 'lo world!'

B 'lo world'

C IndexError

D 'lo worl'

💡 Hint

Slicing does not raise errors if stop index is beyond string length.

Slicing stops at the string end if the stop index is too large. text[3:] is from index 3 to end: 'lo world'.

❓ Predict Output

advanced

Slicing with step zero

What happens when you run this code?

text = 'example'
result = text[::0]
print(result)

Python

text = 'example'
result = text[::0]
print(result)

A ValueError

B '' (empty string)

C 'example'

D TypeError

💡 Hint

Step cannot be zero in slicing.

Using step=0 in slicing raises ValueError: slice step cannot be zero.

🧠 Conceptual

expert

Understanding slice indices with negative start and stop

Given the string s = 'abcdefgh', what is the output of s[-3:-7:-1]?

Python

s = 'abcdefgh'
print(s[-3:-7:-1])

A 'defg'

B 'efgh'

C 'dcba'

D 'fedc'

💡 Hint

Negative indices count from the end. The slice goes backwards from -3 to -7 (excluded).

Index -3 is 'f' (index 5), -7 is 'b' (index 1). The slice goes backwards from index 5 down to 2 inclusive, so 'f','e','d','c'.