REP.ST - replace a substring.

Usage:

B:
   rep.st(string, start, newstr [, leng]);

C:
   #equate rep_st rep.st
   void rep_st(char *string, int start,
               const char *newstr [, int leng] );

Where:

string: is the string in which a substring is to be replaced.
start: is the character position in "string" where the replacement is to start.
newstr: is the substring to be placed in "string".
leng: is the number of characters in "string" to be replaced. If not specified, it defaults to "length(string) - start" so that the remainder of the string is replaced.

Description:

REP.ST is used to replace a substring inside a string and shuffle the rest of the string appropriately. By specifying a null replacement string, REP.ST may be used to delete characters from a string. If "leng" is zero, nothing will be deleted and the characters in "newstr" will be inserted before the character at "start".