最透彻的关于“随机数种子”和“伪随机数”的产生原理

文章转自：http://blog.csdn.net/xzp7772009/article/details/7849030
版权归原作者！

//rand01.c
#include

static unsigned int RAND_SEED;

unsigned int random(void)
{
RAND_SEED=(RAND_SEED*123+59)%65536;
return(RAND_SEED);
}

void random_start(void)
{
int temp[2];
movedata(0x0040,0x006c,FP_SEG(temp),FP_OFF(temp),4);
RAND_SEED=temp[0];
}

main()
{
unsigned int i,n;
random_start();
for(i=0;i<10;i++)
printf("%u\t",random());
printf("\n");
}

//rand02.cpp
#include 
#include 
using namespace std;

int main()
{
unsigned int seed=5;
srand(seed);
unsigned int r=rand();
cout<

//rand03.cpp
#include 
#include 
using namespace std;

int main()
{
srand((unsigned)time(NULL));
unsigned int r=rand();
cout<return 0;
}

//rand04.cpp
#include
#include
using namespace std;
int main()
{
int rNum,m=20;
char *ch=new char[m];

for ( int i = 0; i//大家看到了，随机种子会随着for循环在程序中设置多次
srand((unsigned)time(NULL));
rNum=1+(int)((rand()/(double)RAND_MAX)*36); //求随机值
switch (rNum){
case 1: ch[i]='a';
break ;
case 2: ch[i]='b';
break ;
case 3: ch[i]='c';
break ;
case 4: ch[i]='d';
break ;
case 5: ch[i]='e';
break ;
case 6: ch[i]='f';
break ;
case 7: ch[i]='g';
break ;
case 8: ch[i]='h';
break ;
case 9: ch[i]='i';
break ;
case 10: ch[i]='j';
break ;
case 11: ch[i]='k';
break ;
case 12: ch[i]='l';
break ;
case 13: ch[i]='m';
break ;
case 14: ch[i]='n';
break ;
case 15: ch[i]='o';
break ;
case 16: ch[i]='p';
break ;
case 17: ch[i]='q';
break ;
case 18: ch[i]='r';
break ;
case 19: ch[i]='s';
break ;
case 20: ch[i]='t';
break ;
case 21: ch[i]='u';
break ;
case 22: ch[i]='v';
break ;
case 23: ch[i]='w';
break ;
case 24: ch[i]='x';
break ;
case 25: ch[i]='y';
break ;
case 26: ch[i]='z';
break ;
case 27:ch[i]='0';
break;
case 28:ch[i]='1';
break;
case 29:ch[i]='2';
break;
case 30:ch[i]='3';
break;
case 31:ch[i]='4';
break;
case 32:ch[i]='5';
break;
case 33:ch[i]='6';
break;
case 34:ch[i]='7';
break;
case 35:ch[i]='8';
break;
case 36:ch[i]='9';
break;
}//end of switch
cout<//end of for loop

cout<return 0;
}