关于rand 函数生成随机数的疑问
//猜幻数游戏
#include <iostream>
#include <cstdlib>
using namespace std;
int main()
{
int magic;
int guess;
magic=rand();
cout<<"Guess the magic number.It is between 0 and 100."<<endl;
for(int i=1;i<=5;i=i+1)
{
cin>>guess;
if(guess==magic)
{
cout<<"***Right***"<<endl;
break;
}
else
{
if(i==5)
cout<<"The"<<i<<"time is wrong .End of game!"<<endl;
else
{
if(guess<magic)
cout<<"You have been wrong for"<<i<<"time(s).Please try a bigger one."<<endl;
else
cout<<"You have been wrong for"<<i<<"time(s).Please try smaller one."<<endl;
}
}
}
return 0;
} 为什么使用C++里生成随机数的函数rand 我的程序每次运行所产生的随机数都是一样的，不是应该随机生成的吗？？？求解释
[解决办法]
使用rand之前 加一个语句:srand(time(NULL))
[解决办法]
// crt_rand.c
// This program seeds the random-number generator
// with the time, then exercises the rand function.
//
#include <stdlib.h>
#include <stdio.h>
#include <time.h>
void SimpleRandDemo( int n )
{
// Print n random numbers.
int i;
for( i = 0; i < n; i++ )
printf( " %6d\n", rand() );
}
void RangedRandDemo( int range_min, int range_max, int n )
{
// Generate random numbers in the half-closed interval
// [range_min, range_max). In other words,
// range_min <= random number < range_max
int i;
for ( i = 0; i < n; i++ )
{
int u = (double)rand() / (RAND_MAX + 1) * (range_max - range_min)
+ range_min;
printf( " %6d\n", u);
}
}
int main( void )
{
// Seed the random-number generator with the current time so that
// the numbers will be different every time we run.
srand( (unsigned)time( NULL ) );
SimpleRandDemo( 10 );
printf("\n");
RangedRandDemo( -100, 100, 10 );
}
