$INDEX Function

$INDEX locates the left‑most position in an alphanumeric expression where a search string can be found. $INDEX returns 0 if the search string is not found in the expression. It returns a value of NULL if the expression or the search string evaluates to NULL.

This function has the following format:

$INDEX (alphanumeric‑expression,SEARCH=substring)

alphanumeric‑expression: Defines the string to scan for the first occurrence of the substring.
Substring: Specifies the alphanumeric identifier, literal, or alpha‑group that is the substring to find. This expression must be surrounded by delimiters if it is an alphanumeric literal. It can be a nullable field.

This function is especially useful for extracting a substring with the $SUBSTR function, as shown in the following example.

Example

Assume that A is a 17‑character alphanumeric expression, B is a five‑character alphanumeric expression, and I is a numeric field.

SET A = 'THESE THREE WORDS'

	SET I = $INDEX (A,SEARCH='THREE')    :result is 7
	SET B = $SUBSTR (A,START=I,LENGTH=5) :result is 'THREE'
	SET B = $INDEX (A, SEARCH= 'TTT')    : result is 0