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 value: False

Return value:

String

Example:

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

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