Ruby - String Operations
Which expression extracts the substring 'cat' from
str = "concatenate"?Which expression extracts the substring 'cat' from str = "concatenate"?
easy📝 Conceptual Q2 of 15
Step-by-Step Solution
Solution:
Step 1: Locate 'cat' in 'concatenate'
The substring 'cat' starts at index 3 (0-based): c(0)o(1)n(2)c(3)a(4)t(5)...Step 2: Use slicing with start index and length
str[3, 3] extracts 3 characters starting at index 3, which is 'cat'.Final Answer:
str[3, 3] -> Option BQuick Check:
Start index + length slicing = correct substring [OK]
Quick Trick: Start index + length extracts substring [OK]
Common Mistakes:
- Off-by-one error in start index
- Using range that includes wrong characters
- Confusing negative index meaning
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