C / C++语言中
rand() 每次产生的随机数一样
int rand( void );
[csharp] #include
#include
#include
int main( void )
{
int i;
// Seed the random-number generator with current time so that
// the numbers will be different every time we run.
//
srand( (unsigned)time( NULL ) );
// Display 10 numbers.
for( i = 0; i < 10;i++ )
printf( " %6d\n", rand() );
printf("\n");
// Usually, you will want to generate a number in a specific range,
// such as 0 to 100, like this:
{
int RANGE_MIN = 0;
int RANGE_MAX = 100;
for (i = 0; i < 10; i++ )
{
int rand100 = (((double) rand() /
(double) RAND_MAX) * RANGE_MAX + RANGE_MIN);
printf( " %6d\n", rand100);
}
}
}
#include
#include
#include
int main( void )
{
int i;
// Seed the random-number generator with current time so that
// the numbers will be different every time we run.
//
srand( (unsigned)time( NULL ) );
// Display 10 numbers.
for( i = 0; i < 10;i++ )
printf( " %6d\n", rand() );
printf("\n");
// Usually, you will want to generate a number in a specific range,
// such as 0 to 100, like this:
{
int RANGE_MIN = 0;
int RANGE_MAX = 100;
for (i = 0; i < 10; i++ )
{
int rand100 = (((double) rand() /
(double) RAND_MAX) * RANGE_MAX + RANGE_MIN);
printf( " %6d\n", rand100);
}
}
}
srand() 可使每次产生的随机数不同，和rand连用
[cpp] #include
#include
#include
using namespace std;
int main()
{
srand((unsigned)time(NULL)); //初始化随机数种子
for ( int i = 0; i < 10; i ++ ) //产生10个随机数
{
cout << rand()%10 << endl;
}
return 0;
}
#include
#include
#include
using namespace std;
int main()
{
srand((unsigned)time(NULL)); //初始化随机数种子
for ( int i = 0; i < 10; i ++ ) //产生10个随机数
{
cout << rand()%10 << endl;
}
return 0;
}
Objective-C语言中
arc4random() 比较精确不需要生成随即种子
使用方法：
[cpp] arc4random() //随机产生任何数
arc4random()%x //产生0~x之间的随机数
(arc4random()%x )+1 //产生1~x之间的随机数
arc4random() //随机产生任何数
arc4random()%x //产生0~x之间的随机数
(arc4random()%x )+1 //产生1~x之间的随机数
random() 需要初始化时设置种子
使用方法：
[cpp] srandom((unsigned int)time(time_t *)NULL); //初始化时，设置下种子就好了。
srandom((unsigned int)time(time_t *)NULL); //初始化时，设置下种子就好了。