How one can Return the Closest Quantity A number of of 10 in C

The problem

Given a quantity return the closest quantity to it that’s divisible by 10.

Instance enter:

22
25
37

Anticipated output:

20
30
40

The answer in C

Possibility 1:

#embody <math.h>

int round_to_10 (int n) {
  return spherical(n / 10.0) * 10;
}

Possibility 2:

int round_to_10(int n) {
  return (n + 5) / 10 * 10;
}

Possibility 3:

int round_to_10 (int n) {
    int r = n % 10;
    if (r > 0)
        return r < 5 ? n - r : n - r + 10;
    else if (r < 0)
        return r > -5 ? n - r : n - r - 10;
    return n;
}

Take a look at instances to validate our answer

#embody <criterion/criterion.h>

extern int round_to_10 (int n);
static void do_test (int n, int anticipated);

Take a look at(tests_suite, sample_tests)
{
  do_test(0, 0);
  do_test(10, 10);
  do_test(22, 20);
  do_test(25, 30);
  do_test(37, 40);
}

static void do_test (int n, int anticipated)
{
  int precise = round_to_10(n);
  cr_assert_eq(precise, anticipated,
    "for n = %d, anticipated %d, however obtained %d",
    n, anticipated, precise
  );
}