LINSTR(array%(), search$ [,start] [,size]))
Returns the position of a search string in a long string.
The returned value is an integer and will be zero if the substring cannot be
found. array%() is the string to be searched and must be a long string
variable. search$ is the substring to look for and it must be a normal
MMBasic string or expression (not a long string). The search is case sensitive.
Normally the search will start at the first character in ' array%()' but the optional third parameter allows the start position of the search to be specified.
If the optional parameter size is specified the search$ is treated as a regular
expression. See Appendix E for the details.