Purpose:

Replaces the substrings of the first argument with a new value if they match the regular expression.

Parameter(s):

String          The string to be checked

String          Regular expression

String          Replacement expression (can contain "\0" for the entire match or "\1"… "\9" for the respective group.

Boolean       (optional) Specifies whether only the first occurrence is to be replaced. Default: False.

Return value:

String

Example:

RegExSubSt$("1234xyz6789","[0-9]+", "a")        Result:  "axyza"

RegExSubSt$("1234xyz6789","[0-9]+", "a")        Result:  "axyz6789"