#
# Find all starting indices of a word inside a larger text.
# This function uses String#index in a loop. The method is efficient
# because Ruby implements substring search in optimized C code.
#
def find_all_occurrences(text, word)
indices = []
# Searching for an empty word is meaningless
return indices if word.empty?
start_pos = 0
#
# Loop:
# - Search for the word starting at `start_pos`.
# - If found, record the index.
# - Move forward by one character to allow overlapping matches.
#
while (index = text.index(word, start_pos))
indices << index
start_pos = index + 1
end
indices
end
# Example usage
text = "the quick brown fox jumps over the lazy dog. the fox is clever."
word = "the"
puts "Text: #{text}"
puts "Word: \"#{word}\"\n\n"
puts "Occurrences at indices:"
find_all_occurrences(text, word).each do |idx|
puts idx
end
#
# run:
#
# Text: the quick brown fox jumps over the lazy dog. the fox is clever.
# Word: "the"
#
# Occurrences at indices:
# 0
# 31
# 45
#
