The string functions that respect double-dot range expressions

1. substr() – Returns a part of a string based on the specified start and length parameters. The double-dot range expression can also be used to specify a range of characters to extract from the string.
2. str_replace() – Replaces all occurrences of a search string with a replacement string in a given string. The search string can be a double-dot range expression, which allows you to replace a range of characters in the string.
3. implode() – Joins an array of strings into a single string, with an optional glue string between each element. The double-dot range expression can be used to specify a range of elements from the array to join together in the resulting string.

"diamond operator" or "splat operator"