/*
Find all starting indices of a word inside a larger text.
This function uses strpos in a loop. The function is efficient
and implemented in optimized C code inside PHP's engine.
*/
function findAllOccurrences(string $text, string $word): array
{
$indices = [];
// Searching for an empty word is meaningless
if ($word === '') {
return $indices;
}
$pos = strpos($text, $word); // First occurrence
while ($pos !== false) {
$indices[] = $pos; // Store the index
/*
Search again starting one character after the previous match.
This allows detection of overlapping matches.
*/
$pos = strpos($text, $word, $pos + 1);
}
return $indices;
}
// Example usage
$text = "the quick brown fox jumps over the lazy dog. the fox is clever.";
$word = "the";
echo "Text: $text\n";
echo "Word: \"$word\"\n\n";
echo "Occurrences at indices:\n";
foreach (findAllOccurrences($text, $word) as $index) {
echo $index . "\n";
}
/*
run:
Text: the quick brown fox jumps over the lazy dog. the fox is clever.
Word: "the"
Occurrences at indices:
0
31
45
*/
