Is there a better way to write these If-Statements?-CodePudding

I'm building a Random Character Generator in C , and I have around 12 large blocks of if statements, like this:

int wisdom = rand() % 18;

cout << "\n";

if (wisdom == 0 || wisdom == 1) {

    cout << "Wisdom Score: 1\n";
    cout << "Modifier: -5\n";

} else if (wisdom == 2 || wisdom == 3) {

    cout << "Wisdom Score: " << wisdom << "\n";
    cout << "Modifier: -4\n";

} else if (wisdom == 4 || wisdom == 5) {

    cout << "Wisdom Score: " << wisdom << "\n";
    cout << "Modifier: -3\n";

} else if (wisdom == 6 || wisdom == 7) {

    cout << "Wisdom Score: " << wisdom << "\n";
    cout << "Modifier: -2\n";

} else if (wisdom == 8 || wisdom == 9) {

    cout << "Wisdom Score: " << wisdom << "\n";
    cout << "Modifier: -1\n";

} else if (wisdom == 10 || wisdom == 11) {

    cout << "Wisdom Score: " << wisdom << "\n";
    cout << "Modifier:  0\n";

} else if (wisdom == 12 || wisdom == 13) {

    cout << "Wisdom Score: " << wisdom << "\n";
    cout << "Modifier:  1\n";

} else if (wisdom == 14 || wisdom == 15) {

    cout << "Wisdom Score: " << wisdom << "\n";
    cout << "Modifier:  2\n";

} else if (wisdom == 16 || wisdom == 17) {

    cout << "Wisdom Score: " << wisdom << "\n";
    cout << "Modifier:  3\n";

} else {

    cout << "Wisdom Score: 18\n";
    cout << "Modifier:  4\n"; 

}

I'm wondering, is there a better way to write this? Perhaps some type of function?

CodePudding user response：

The better way is to not write chained ifs at all, but instead compute the value you care about.

if (wisdom == 0) wisdom = 1; // Handle edge case treating 0 as 1
int modifier = wisdom / 2 - 5;

cout << "Wisdom Score: " << wisdom << '\n';
cout << "Modifier: " << modifier << '\n';

Note that your calculation of int wisdom = rand() % 18; cannot produce 18 (and does produce 0, which you don't want), so you probably want to change it to:

int wisdom = rand() % 18   1;  // Result guaranteed to be 1-18 inclusive

allowing you to simplify the code by removing the if (wisdom == 0) wisdom = 1; edge case.

As another answer has already noted, rand is typically considered a bad API, so unless you're okay with biased results (e.g. slightly more low rolls than high rolls), you'll want to use modern C PRNG APIs (they're a little more work to set up, but trivial to use once you've done so, and they should avoid bias issues).

CodePudding user response：

Use the fact that the division of 2 integral values results in the trucation of the result:

...
int modifier = (wisdom / 2) - 5;

CodePudding user response：

You don't need any conditionals. Also, don't use rand() %.

std::mt19937 mt(42); // seed
auto const wisdom = std::uniform_int_distribution<int>(0,18)(mt);
auto const score = wisdom   !wisdom;
auto const mod = wisdom / 2 - 5;

std::cout << "Wisdom Score: " << score << "\n";
std::cout << "Modifier: " << mod << "\n";

This assumes it is intentional that you have a double chance of wisdom score 1 proccing compared to other scores. If not change the lower bound in the std::uniform_int_distribution construction from 1 to 0.