PROGRAM STRINGS; {a demo of the built-in string operations}
VAR
  S1:STRING;
  S2:STRING;
  POSN:INTEGER;

BEGIN
  CURSOR(0,0);
  WRITELN('strings demo program');
  REPEAT
    WRITE('enter string 1: ');
    READLN(S1);
    WRITE('enter pos: ');
    READLN(POSN);
    WRITE('enter string to insert: ');
    READLN(S2);
    WRITELN(S1,'-',POSN:1,'-',S2);
    INSERT(S1,POSN,S2);         {insert S2 in S1 starting at S1[POSN] }
    WRITELN('S1 =',S1,'.');
  UNTIL S1 = 'stop';
END.