随机发生数函数rand及初始化种子数srand,rand使用强制转换

unsigned long int next = 1;

/*rand:return paeudo-random integer on 0..*/
int rand(void)
{
    next = next * 1103515245 + 12345;
    return (unsigned int)(next / 65536)%32768;
}

/*srand: set seed for rand*/
void srand(unsigned int seed)
    {
        next = seed;
    }