[C / C ++] generating random numbers

C / C ++: rand () function

rand () function in the header file: #include <stdlib.h>

Randomness of the random numbers generated by a difference function, slow, small period (0-32767)

Are used as follows:

. 1 #include <stdio.h>
 2 #include <stdlib.h>
 . 3 #include <time.h>
 . 4  int main ()
 . 5  {
 . 6      srand ((unsigned int ) Time ( 0 )); /// to lapse system time of the random number generator seed 
. 7      for ( int I = 0 ; I < 10 ; I ++ )
 . 8      {
 . 9          int (n-= RAND ()% 50 - 25 ) + 25 ; /// random integer generated between 25-50 , rand% (ba) + a which produce [a, random integers in b) the range of 
10          Double D = RAND () / (Double ) and RAND_MAX; /// generating a random decimal 0-1 
. 11          the printf ( " % D% F \ n- " , n-, D);
 12 is      }
 13 is      the puts ( "" );
 14      the printf ( " RAND () function can be generated random number range: 0-% D \ n- " , and RAND_MAX);
 15      return  0 ;
 16 }

Code results are as follows:

C++11：mt19937

mt19937 header file: #include <random>

Generating speed, large period (0-4294967295)

Usage above rand () Similarly, as shown below:　

 1 #include<random>
 2 #include<time.h>
 3 #include<bits/stdc++.h>
 4 using namespace std;
 5 int main()
 6 {
 7     mt19937 mt_rand(chrono::high_resolution_clock::now().time_since_epoch().count());///随机种子
 8     ///或用：mt19937 mt_rand(time(0));
 9     for(int i=0;i<10;i++)
10     {
11         int n=mt_rand()%(1000-25)+25; /// generates random integer between 25-1000 
12 is          the printf ( " % D \ n- " , n-);
 13 is      }
 14      return  0 ;
 15 }

Random library using a random number generator, used as follows:

. 1 #include <the iostream>
 2 #include <Random>
 . 3  the using  namespace STD;
 . 4  
. 5  int main ()
 . 6  {
 . 7      mt19937 are RNG;
 . 8      rng.seed (random_device () ()); // initialize the random seed 
. 9  
10      uniform_int_distribution < int > int_dist ( 1 , 100 ); // create a uniform distribution equiprobable (random) to generate [1, 100] interval digital shaping; 
. 11      uniform_real_distribution < Double > real_dist (- 1 , 1 ); //Creating a uniform distribution (equiprobable) randomly generated between the (-1, 1) decimal; 
12 is  
13 is      for ( int I = 0 ; I < 10 ; I ++ ) {
 14          COUT << int_dist (RNG) << '  ' ;
 15          COUT << real_dist (RNG) << endl;
 16      }
 . 17      return  0 ;
 18 is }

Results are as follows:

C ++ Standard Library --random