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rand() function generates the next number by ascending to the previous number

How to generate a random number in C++?Generating random integer from a rangeuse of srand() in c++How do I generate a random number using the C++11 standard librarygenerating Random numbers using rand()srand(time(NULL)): error C4430: missing type specifier - int assumed. Note: C++ does not support default-intimplementation of the random number generator in C/C++<random> generates same number in Linux, but not in WindowsCorrect c++ codes get warnings in EclipseFormula used for function rand() in c++Suggestions for new tweak in C++ for generating random numbers

.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;

-1

Please check code given below. The random number it generates for each execution is the increment of the previous generated number in the previous execution.

#include <iostream>
#include <ctime>
#include <cstdlib>

using namespace std;

int main()

 srand(time(NULL));

 cout<<"n Random Number : "<<rand()<<endl;

 cin.get();
 return 1;

Please executeit for 5-6 times and you will see that the random numbers are increasing for each execution and they are very close to each other.

Note : Please use CodeBlocks or Visual studio to check it, not the online compilers.

c++

share|improve this question

edited Mar 28 at 7:59

bashburak

asked Mar 27 at 14:23

bashburakbashburak

7411 silver badge55 bronze badges

• 
  
  
  

  
  4
  

  
  
  
  
  
  

  
  
  There are almost no guaranties on the randomness of rand(). Your behavior may be due to the fact that srand is seeded with slightly larger values (the current time) each time you test. It might just be returning the seed on the first call each time, or something closely related to it.
  
  – François Andrieux
  Mar 27 at 14:25
  
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  time(NULL) gives you the time in seconds as an integer, so if you call the program twice in the same second, you will get the same number twice. If you call it in the next second, you will get completely different numbers: ideone.com/McE7CD
  
  – mch
  Mar 27 at 14:30
  

  
  
  
  


• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  moreover you seem to compare random numbers where each is generated with a different seed, where the seed have a strong relation. To get anything meaning full you would have to look at lots of random numbers generated from the same seed
  
  – formerlyknownas_463035818
  Mar 27 at 14:31
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Duplicate of stackoverflow.com/questions/13445688/… ?
  
  – William D. Irons
  Mar 27 at 14:34
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Possible duplicate of How to generate a random number in C++?
  
  – Flau
  Mar 28 at 11:36
  

  
  
  
  

 | 
show 5 more comments

-1

Please check code given below. The random number it generates for each execution is the increment of the previous generated number in the previous execution.

#include <iostream>
#include <ctime>
#include <cstdlib>

using namespace std;

int main()

 srand(time(NULL));

 cout<<"n Random Number : "<<rand()<<endl;

 cin.get();
 return 1;

Please executeit for 5-6 times and you will see that the random numbers are increasing for each execution and they are very close to each other.

Note : Please use CodeBlocks or Visual studio to check it, not the online compilers.

c++

share|improve this question

edited Mar 28 at 7:59

bashburak

asked Mar 27 at 14:23

bashburakbashburak

7411 silver badge55 bronze badges

• 
  
  
  

  
  4
  

  
  
  
  
  
  

  
  
  There are almost no guaranties on the randomness of rand(). Your behavior may be due to the fact that srand is seeded with slightly larger values (the current time) each time you test. It might just be returning the seed on the first call each time, or something closely related to it.
  
  – François Andrieux
  Mar 27 at 14:25
  
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  time(NULL) gives you the time in seconds as an integer, so if you call the program twice in the same second, you will get the same number twice. If you call it in the next second, you will get completely different numbers: ideone.com/McE7CD
  
  – mch
  Mar 27 at 14:30
  

  
  
  
  


• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  moreover you seem to compare random numbers where each is generated with a different seed, where the seed have a strong relation. To get anything meaning full you would have to look at lots of random numbers generated from the same seed
  
  – formerlyknownas_463035818
  Mar 27 at 14:31
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Duplicate of stackoverflow.com/questions/13445688/… ?
  
  – William D. Irons
  Mar 27 at 14:34
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Possible duplicate of How to generate a random number in C++?
  
  – Flau
  Mar 28 at 11:36
  

  
  
  
  

 | 
show 5 more comments

Please check code given below. The random number it generates for each execution is the increment of the previous generated number in the previous execution.

#include <iostream>
#include <ctime>
#include <cstdlib>

using namespace std;

int main()

 srand(time(NULL));

 cout<<"n Random Number : "<<rand()<<endl;

 cin.get();
 return 1;

Please executeit for 5-6 times and you will see that the random numbers are increasing for each execution and they are very close to each other.

Note : Please use CodeBlocks or Visual studio to check it, not the online compilers.

c++

share|improve this question

edited Mar 28 at 7:59

bashburak

asked Mar 27 at 14:23

bashburakbashburak

7411 silver badge55 bronze badges

#include <iostream>
#include <ctime>
#include <cstdlib>

using namespace std;

int main()

 srand(time(NULL));

 cout<<"n Random Number : "<<rand()<<endl;

 cin.get();
 return 1;

share|improve this question

edited Mar 28 at 7:59

bashburak

asked Mar 27 at 14:23

bashburakbashburak

7411 silver badge55 bronze badges

share|improve this question

edited Mar 28 at 7:59

bashburak

asked Mar 27 at 14:23

bashburakbashburak

7411 silver badge55 bronze badges

asked Mar 27 at 14:23

bashburakbashburak

7411 silver badge55 bronze badges

asked Mar 27 at 14:23

bashburakbashburak

7411 silver badge55 bronze badges

1 Answer
1

active

oldest

votes

-1

Actually I found a way to solve my problem but still it might not be an answer to my question.
Anyway the problem is not about srand() or rand() functions but it is about the function time(NULL). Since I am trying to run this code on Windows, instead of using time(NULL) as a parameter for srand(), I used GetTickCount() and now it generates random numbers properly for each execution.

#include <iostream>
#include <cstdlib>
#include <windows.h>

using namespace std;

int main()

 srand(GetTickCount());

 cout<<"n Random Number : "<<rand();

 cout<<"n";
 cin.get();
 return 1;

share|improve this answer

answered Mar 28 at 9:55

bashburakbashburak

7411 silver badge55 bronze badges

add a comment | 

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-1

Actually I found a way to solve my problem but still it might not be an answer to my question.
Anyway the problem is not about srand() or rand() functions but it is about the function time(NULL). Since I am trying to run this code on Windows, instead of using time(NULL) as a parameter for srand(), I used GetTickCount() and now it generates random numbers properly for each execution.

#include <iostream>
#include <cstdlib>
#include <windows.h>

using namespace std;

int main()

 srand(GetTickCount());

 cout<<"n Random Number : "<<rand();

 cout<<"n";
 cin.get();
 return 1;

share|improve this answer

answered Mar 28 at 9:55

bashburakbashburak

7411 silver badge55 bronze badges

add a comment | 

-1

Actually I found a way to solve my problem but still it might not be an answer to my question.
Anyway the problem is not about srand() or rand() functions but it is about the function time(NULL). Since I am trying to run this code on Windows, instead of using time(NULL) as a parameter for srand(), I used GetTickCount() and now it generates random numbers properly for each execution.

#include <iostream>
#include <cstdlib>
#include <windows.h>

using namespace std;

int main()

 srand(GetTickCount());

 cout<<"n Random Number : "<<rand();

 cout<<"n";
 cin.get();
 return 1;

share|improve this answer

answered Mar 28 at 9:55

bashburakbashburak

7411 silver badge55 bronze badges

add a comment | 

Actually I found a way to solve my problem but still it might not be an answer to my question.
Anyway the problem is not about srand() or rand() functions but it is about the function time(NULL). Since I am trying to run this code on Windows, instead of using time(NULL) as a parameter for srand(), I used GetTickCount() and now it generates random numbers properly for each execution.

#include <iostream>
#include <cstdlib>
#include <windows.h>

using namespace std;

int main()

 srand(GetTickCount());

 cout<<"n Random Number : "<<rand();

 cout<<"n";
 cin.get();
 return 1;

share|improve this answer

answered Mar 28 at 9:55

bashburakbashburak

7411 silver badge55 bronze badges

#include <iostream>
#include <cstdlib>
#include <windows.h>

using namespace std;

int main()

 srand(GetTickCount());

 cout<<"n Random Number : "<<rand();

 cout<<"n";
 cin.get();
 return 1;

share|improve this answer

answered Mar 28 at 9:55

bashburakbashburak

7411 silver badge55 bronze badges

answered Mar 28 at 9:55

bashburakbashburak

7411 silver badge55 bronze badges

answered Mar 28 at 9:55

bashburakbashburak

7411 silver badge55 bronze badges