Safe addition: Difference between revisions

=={{header|C++}}==

{{trans|C#}}

<lang cpp>#include <iostream>

#include <tuple>

union conv {

int i;

float f;

};

float nextUp(float d) {

if (isnan(d) || d == -INFINITY || d == INFINITY) return d;

if (d == 0.0) return FLT_EPSILON;

conv c;

c.f = d;

c.i++;

return c.f;

}

float nextDown(float d) {

if (isnan(d) || d == -INFINITY || d == INFINITY) return d;

if (d == 0.0) return -FLT_EPSILON;

conv c;

c.f = d;

c.i--;

return c.f;

}

auto safeAdd(float a, float b) {

return std::make_tuple(nextDown(a + b), nextUp(a + b));

}

int main() {

float a = 1.20f;

float b = 0.03f;

auto result = safeAdd(a, b);

printf("(%f + %f) is in the range (%0.16f, %0.16f)\n", a, b, std::get<0>(result), std::get<1>(result));

return 0;

}</lang>

{{out}}

<pre>(1.200000 + 0.030000) is in the range (1.2299998998641968, 1.2300001382827759)</pre>