1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
|
#include "c23-fallback.h"
#include <stdio.h>
#include <fenv.h>
#include <float.h>
#ifndef INFINITY
#include <math.h>
#endif
#if !defined(__STDC_IEC_559__) && !defined(__STDC_IEC_60559_BFP__) && !FE_ALL_EXCEPT
#error "floating-point arithmetic is too weird"
#endif
static_assert(FE_ALL_EXCEPT, "floating point exceptions are not supported");
#ifdef FENV_OFF
#warning "switching FENV_ACCESS off"
#pragma STDC FENV_ACCESS OFF
#else
#pragma STDC FENV_ACCESS ON
#endif
bool const has_inf =
#ifdef INFINITY
(1.0/0.0 == INFINITY)
#else
false
#endif
;
int excepts[] = {
#ifdef FE_DIVBYZERO
FE_DIVBYZERO,
#endif
#ifdef FE_INEXACT
FE_INEXACT,
#endif
#ifdef FE_INVALID
FE_INVALID,
#endif
#ifdef FE_OVERFLOW
FE_OVERFLOW,
#endif
#ifdef FE_UNDERFLOW
FE_UNDERFLOW,
#endif
};
void printexcept(void) {
char const* name[] = {
#ifdef FE_DIVBYZERO
"divbyzero",
#endif
#ifdef FE_INEXACT
"inexact",
#endif
#ifdef FE_INVALID
"invalid",
#endif
#ifdef FE_OVERFLOW
"overflow",
#endif
#ifdef FE_UNDERFLOW
"underflow",
#endif
};
int except = fetestexcept(FE_ALL_EXCEPT);
if (except) {
printf("[");
for (unsigned j = 0; except; except &= ~excepts[j], ++j)
if (excepts[j] & except)
printf("%s ", name[j]);
printf("]");
}
}
int main (int argc, char* argv[static argc+1]) {
printf("division by zero is %sequal to INFINITY\n", has_inf ? "" : "un");
for (unsigned i = 1; i < argc; i++) {
feclearexcept(FE_ALL_EXCEPT);
double x = strtod(argv[i], nullptr);
printf("%g ", x);
printexcept();
feclearexcept(FE_ALL_EXCEPT);
printf(": %g ", 1.0/x);
printexcept();
puts("");
}
}
|
