32位随机数

                                                  

                                                    软件架构师何志丹

声明

　class DLL_SN_EXT_CLASS CRand32
{
public:
CRand32();
unsigned int rand();
bool Prize(double dOdds);//中奖几率,dOdds<=0,必定不中;dOdds>=1 必中
protected:
unsigned int m_iSeed; /* Seed variables */
static int s_iObjNum;
};

优点：

一，不需要随机种子，多个对象会随机不同的种子。　

二，范围和UINT的范围同

实现

int CRand32::s_iObjNum = 0;
CRand32::CRand32()
{
m_iSeed = ::time(NULL) + s_iObjNum++;
}

unsigned int CRand32::rand()
{
m_iSeed = 214013 * m_iSeed + 2531011;
return m_iSeed;
}
bool CRand32::Prize(double dOdds)//中奖几率,dOdds<=0,必定不中;dOdds>=1 必中
{
return (double)rand() / UINT_MAX < dOdds;
}

测试样例

TEST_METHOD(RAND32_1)
{// n 个对象的第一个随机数，一定不相同
const int n = 100;
SN::CRand32 rs[n];
int iRs[n] = { 0 };

{
for (int i = 0; i < n; i++)
{
iRs[i] = rs[i].rand();
}
}
{
for( int i = 0 ; i < n ; i++ )
for (int j = i + 1; j < n; j++)
{
Assert::AreNotEqual(iRs[i], iRs[j]);
}
}
}

TEST_METHOD(RAND32_2)
{//随机次数足够多，每位为0,1的几率稳定（正负10%）
SN::CRand32 rand ;

int a[32] = { 0 };
const int iNum = 10000000;
for (int i = 0; i < iNum; i++)
{
unsigned int r = rand.rand();
for (int j = 0; j < 32; j++)
{
a[j] += ((r >> j) & 0x1);
}
}

{
for (int i = 0; i < 32; i++)
{
CString s;
s.Format(_T("%d"), i);
Assert::IsTrue(abs(a[i] - iNum / 2) < iNum / 20,s);
}
}
}

TEST_METHOD(RAND32_3)
{
SN::CRand32 r;
const int iNum = 10000000;
int a[5] = { 0 };
for (int i = 0; i < iNum; i++)
{
a[0] += r.Prize(0);
a[1] += r.Prize(0.0001);
a[2] += r.Prize(0.5);
a[3] += r.Prize(0.99);
a[4] += r.Prize(100);
}

Assert::AreEqual(a[0], 0);
Assert::IsTrue(abs(a[1]- iNum / 10000) < iNum / 100000);
Assert::IsTrue(abs(a[2] - iNum / 2) < iNum / 20);
Assert::IsTrue(abs(a[3] - iNum *0.99) < iNum *0.99/ 10);
Assert::AreEqual(a[4], iNum);
}