rint.c

rint.c

#include <stdio.h>
#include <math.h>
#include <fenv.h>

#define _(x) { x, #x }
static struct { int mode; char *name; } modes[] = {
  _(FE_DOWNWARD),
  _(FE_TONEAREST),
  _(FE_TOWARDZERO),
  _(FE_UPWARD),
};

static double data[] = {
  1.25, 1.5, 1.75, 2.5, -1.25, -1.5, -1.75, -2.5
};

int main(int argc, char **argv) {

  int i, j;
  int ok;

  for (i = 0; i < 4; ++i) {
    ok = fesetround(modes[i].mode);
    printf("fesetround(%s): %d\n", modes[i].name, ok);
    for (j = 0; j < 8; ++j) {
      printf("rint(%f): %f\n", data[j], rint(data[j]));
    }
  }
  return 0;
}