1(*
2 * Copyright (c) 1980, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * %sccs.include.redist.c%
6 *
7 *	@(#)overflow.p	8.1 (Berkeley) 06/06/93
8 *)
9
10program fpexceptions(input,output);
11    type
12	fperrorkind = ( fperrorfirst,
13			overflow,underflow,divideby0,domain,
14			fperrolast );
15    var
16	request : fperrorkind;
17    procedure genoverflow;
18	var
19	    i : integer;
20	    r : real;
21	begin
22	    r := 2.0;
23	    for i := 1 to 1000 do begin
24		r := r * r;
25	    end;
26	    writeln('this machine handles more than 2^1000');
27	end;
28    procedure genunderflow;
29	var
30	    i : integer;
31	    r : real;
32	begin
33	    r := 0.5;
34	    for i := 1 to 1000 do begin
35		r := r * r;
36	    end;
37	    writeln('this machine handles more than 2^-1000');
38	end;
39    procedure gendivideby0;
40	var
41	    r : real;
42	begin
43	    r := 17.0;
44	    r := r - r;		{should be 0.0}
45	    r := 17.0 / r;
46	    writeln('i wonder what r is?', r);
47	end;
48    procedure gendomain;
49	var
50	    r : real;
51	begin
52	    r := -17.0;
53	    r := sqrt(r);
54	    writeln('i wonder what r is?', r);
55	end;
56    begin
57	write('which do you want (');
58	for request := succ(fperrorfirst) to pred(fperrolast) do begin
59		{this isn't standard pascal.}
60	    write( ' ', request);
61	end;
62	write(' ): ');
63	    {neither is this, but it sure is convenient.}
64	readln(request);
65	if request in [overflow,underflow,divideby0,domain] then begin
66	    writeln('one ', request, ' coming right down');
67	    case request of
68		overflow:	genoverflow;
69		underflow:	genunderflow;
70		divideby0:	gendivideby0;
71		domain:	gendomain;
72	    end;
73	end else begin
74		{default:}
75	    writeln('oh, never mind');
76	end;
77    end.
78
79