DECLARE SUB SELECT1 (X%(), N%)
DEFINT A-Z
CLS
DIM A(20)
FOR J = 0 TO 19: A(J) = INT(20 * RND): PRINT USING "####"; A(J); : NEXT J
PRINT
SELECT1 A(), 20
FOR J = 0 TO 19: PRINT USING "####"; A(J); : NEXT J
END

DEFSNG A-Z
SUB SELECT1 (X%(), N%)
DEFINT A-Z
FOR I = 0 TO N - 2
  Q = 0: K = I: TMP = X(I)
  FOR J = I + 1 TO N - 1
    IF X(J) < TMP THEN K = J: TMP = X(J): Q = 1
  NEXT J
  IF Q = 1 THEN X(K) = X(I): X(I) = TMP
NEXT I
END SUB