C++ Rnd() 故障

Question

伙计们，我在运行程序时遇到了这个非常奇怪的错误。这是重要的代码:

变量(编辑):

const short int maxX = 100;
const short int maxZ = 100;
const short int lakeChance = 0.9;

addLake 函数(编辑):

void addLake(Sect sector[][maxZ], int x, int z){    
    sector[x][z].setMaterial(1);
}

主要来源(编辑):

//Generating land mass
for (int x = 0; x < maxX; x++){
    for (int z = 0; z < maxZ; z++){
        //Default material
        sector[x][z].setMaterial(0);

        //Add lake/sea source
        int r = rand();
        float r1 = (r % 1000);
        float r2 = r1 / 1000;

        if (r2 <= lakeChance) addLake(sector, x, z);
    }
}

错误是，无论我将“lakeChance”值更改为什么，结果似乎都完全相同。尽管我将 lakeChance 的值更改得更高(即:0.5、0.7、0.9)，但在每次启动时似乎都会调用 addLake 函数约 3 到 6 次。只有当我将“lakeChance”的值更改为 1 时，该函数才会一直被调用。顺便说一句，随机数生成器工作正常，所以结果每次都会有所不同。

Answer 1

我没有看到显然本身有什么问题。所以我尝试了以下代码:

int test(float chance)
{
    int call = 0;

    for(int i = 0; i != 100000; i++)
    {
        int r = rand();

        float r1 = (r % 1000);

        float r2 = r1 / 1000;

        if(r2 <= chance)
            call++;
    }

    cout << "Chance is " << chance << ": " << call << " invocations or "
         << ((100.0 * call) / 100000.0) << "% of the time!" << endl;

    return call;    
}

不出所料，我得到了这些结果:

Chance is 0.1: 10216 invocations or 10.216% of the time!
Chance is 0.2: 20232 invocations or 20.232% of the time!
Chance is 0.3: 30357 invocations or 30.357% of the time!
Chance is 0.4: 40226 invocations or 40.226% of the time!
Chance is 0.6: 60539 invocations or 60.539% of the time!
Chance is 0.7: 70539 invocations or 70.539% of the time!
Chance is 0.8: 80522 invocations or 80.522% of the time!
Chance is 0.9: 90336 invocations or 90.336% of the time!
Chance is 1: 100000 invocations or 100% of the time!

您要添加多少个湖泊？