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"