DaniWeb Forum Index > Software Development > C++

C++ RSS

Random number sequences

Please support our C++ advertiser: Intel Parallel Studio Home

Thread Solved

•

Join Date: Jun 2008

Posts: 10

Reputation: Superfat is an unknown quantity at this point

Solved Threads: 0

Superfat

Offline

Newbie Poster

Random number sequences

Jun 22nd, 2008

I know about using ran() to create a random number between x and y, however i am creating a banking program and i am wondering how to randomly generate a 17 digit pin, then store the pin in an outside file, then have the program check the file for the pin

•

Join Date: Dec 2006

Posts: 1,089

Reputation: vijayan121 is a name known to all

Solved Threads: 164

vijayan121 vijayan121 is offline

Offline

Veteran Poster

Re: Random number sequences

Jun 22nd, 2008

 Help with Code Tags 
 c++ Syntax (Toggle Plain Text) 
#include <cstdlib>
#include <string>
 
inline char random_digit() { return '0' + std::rand() % 10 ; }
 
inline std::string random_pin( std::size_t ndigits )
{
  std::string pin ;
  for( std::size_t i = 0 ; i < ndigits ; ++i ) pin += random_digit() ;
  return pin ;
}
#include <cstdlib>
#include <string>

inline char random_digit() { return '0' + std::rand() % 10 ; }

inline std::string random_pin( std::size_t ndigits )
{
  std::string pin ;
  for( std::size_t i = 0 ; i < ndigits ; ++i ) pin += random_digit() ;
  return pin ;
}

•

Join Date: Jun 2008

Posts: 10

Reputation: Superfat is an unknown quantity at this point

Solved Threads: 0

Superfat

Offline

Newbie Poster

Re: Random number sequences

Jun 22nd, 2008

I tried it, and recieved an error,

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
 [Linker error] undefined reference to `WinMain@16'
 
 [Linker error] undefined reference to `WinMain@16'

•

Join Date: Oct 2006

Posts: 514

Reputation: Jishnu will become famous soon enough

Solved Threads: 26

Jishnu

Offline

Posting Pro

Re: Random number sequences

Jun 22nd, 2008

vijayan121 has just provided the functions, you'll have to adapt them according to your main code and use them. His functions will compile, but how do you expect them to run?!

"You know you're a computer geek when you try to shoo a fly away from the monitor screen with your cursor. That just happened to me. It was scary." - Juuso Heimonen.

"The only truly secure computer is one buried in concrete, with the power turned off and the network cable cut." - Anonymous.

•

Join Date: Nov 2007

Posts: 978

Reputation: mitrmkar is just really nice

Solved Threads: 208

mitrmkar

Offline

Posting Shark

Re: Random number sequences

Jun 22nd, 2008

•

Originally Posted by Superfat

I tried it, and recieved an error,
Help with Code Tags

C++ Syntax (Toggle Plain Text)
 [Linker error] undefined reference to `WinMain@16'
 
[Linker error] undefined reference to `WinMain@16'

You are trying to build a Win 32 GUI program and you have no WinMain(...) - hence the error.
If you want to build a GUI program, then write the WinMain(...) too, see
http://msdn.microsoft.com/en-us/library/ms633559.aspx

Otherwise, start a new Win32 Console Application project, which uses the int main() .

•

Join Date: Jun 2008

Posts: 10

Reputation: Superfat is an unknown quantity at this point

Solved Threads: 0

Superfat

Offline

Newbie Poster

Re: Random number sequences

Jun 22nd, 2008

Okay, i tried something that i thought up, reading up i remembered that a 17 digit number isnt really possible in C++... so i have come up with this, however i am getting two errors, i think it has something to do with the brackets... but i cant figure anything out

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
      #include <cstdio>
      #include <cstdlib>
      #include <ctime>
      #include <iostream>
 
      using namespace std;
      int main(int nNumberofArgs, char* pszArgs[])
   {  
     srand ( (unsigned)time ( 0 ) );
 
     const int a = rand() % 9 ;
     const int b = rand() % 9 ;
     const int c = rand() % 9 ;
     const int d = rand() % 9 ;
     const int e = rand() % 9 ;
     const int f = rand() % 9 ;
     const int g = rand() % 9 ;
     const int h = rand() % 9 ;
     const int i = rand() % 9 ;
     const int j = rand() % 9 ;
     const int k = rand() % 9 ;
     const int l = rand() % 9 ;
     const int m = rand() % 9 ;
     const int n = rand() % 9 ;
     const int o = rand() % 9 ;
     const int p = rand() % 9 ;
     const int q = rand() % 9 ;
     const int r = rand() % 9 ;
{
      char transactionType;      
      cout << "Press N to cancel, and Y to continue:\n " << endl;
      cin  >> transactionType;
 
       if (transactionType == 'x' ||
           transactionType == 'X')
       {
           break;
       }
 
      if (transactionType == 'y' ||
          transactionType == 'y')
       {
 
continue ;
 
       }
     }
    {   
       cout << "abcdefghijklmnopqr";
      }
    }
      #include <cstdio>
      #include <cstdlib>
      #include <ctime>
      #include <iostream>
      
      using namespace std;
      int main(int nNumberofArgs, char* pszArgs[])
   {  
     srand ( (unsigned)time ( 0 ) );
      
     const int a = rand() % 9 ;
     const int b = rand() % 9 ;
     const int c = rand() % 9 ;
     const int d = rand() % 9 ;
     const int e = rand() % 9 ;
     const int f = rand() % 9 ;
     const int g = rand() % 9 ;
     const int h = rand() % 9 ;
     const int i = rand() % 9 ;
     const int j = rand() % 9 ;
     const int k = rand() % 9 ;
     const int l = rand() % 9 ;
     const int m = rand() % 9 ;
     const int n = rand() % 9 ;
     const int o = rand() % 9 ;
     const int p = rand() % 9 ;
     const int q = rand() % 9 ;
     const int r = rand() % 9 ;
{
      char transactionType;      
      cout << "Press N to cancel, and Y to continue:\n " << endl;
      cin  >> transactionType;

       if (transactionType == 'x' ||
           transactionType == 'X')
       {
           break;
       }
       
      if (transactionType == 'y' ||
          transactionType == 'y')
       {
       
continue ;
       
       }
     }
    {   
       cout << "abcdefghijklmnopqr";
      }
    }

errors:

Help with Code Tags

C++ Syntax (Toggle Plain Text)

break statement not within
continue statement not within

•

Join Date: Aug 2005

Posts: 5,264

Reputation: iamthwee is a splendid one to behold

Solved Threads: 377

iamthwee

Offline

Posting Expert

Re: Random number sequences

Jun 22nd, 2008

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <iostream>
 
using namespace std;
int main ( int nNumberofArgs, char* pszArgs[] )
{
  srand ( ( unsigned ) time ( 0 ) );
 
  const int a = rand() % 9 ;
  const int b = rand() % 9 ;
  const int c = rand() % 9 ;
  const int d = rand() % 9 ;
  const int e = rand() % 9 ;
  const int f = rand() % 9 ;
  const int g = rand() % 9 ;
  const int h = rand() % 9 ;
  const int i = rand() % 9 ;
  const int j = rand() % 9 ;
  const int k = rand() % 9 ;
  const int l = rand() % 9 ;
  const int m = rand() % 9 ;
  const int n = rand() % 9 ;
  const int o = rand() % 9 ;
  const int p = rand() % 9 ;
  const int q = rand() % 9 ;
  const int r = rand() % 9 ;
  {
    char transactionType;
    cout << "Press N to cancel, and Y to continue:\n " << endl;
    cin  >> transactionType;
 
    if ( transactionType == 'x' ||
         transactionType == 'X' )
    {
      break;
    }
 
    if ( transactionType == 'y' ||
         transactionType == 'y' )
    {
      continue ;
    }
  }
  {
    cout << "abcdefghijklmnopqr";
  }
}
#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <iostream>

using namespace std;
int main ( int nNumberofArgs, char* pszArgs[] )
{
  srand ( ( unsigned ) time ( 0 ) );

  const int a = rand() % 9 ;
  const int b = rand() % 9 ;
  const int c = rand() % 9 ;
  const int d = rand() % 9 ;
  const int e = rand() % 9 ;
  const int f = rand() % 9 ;
  const int g = rand() % 9 ;
  const int h = rand() % 9 ;
  const int i = rand() % 9 ;
  const int j = rand() % 9 ;
  const int k = rand() % 9 ;
  const int l = rand() % 9 ;
  const int m = rand() % 9 ;
  const int n = rand() % 9 ;
  const int o = rand() % 9 ;
  const int p = rand() % 9 ;
  const int q = rand() % 9 ;
  const int r = rand() % 9 ;
  {
    char transactionType;
    cout << "Press N to cancel, and Y to continue:\n " << endl;
    cin  >> transactionType;

    if ( transactionType == 'x' ||
         transactionType == 'X' )
    {
      break;
    }

    if ( transactionType == 'y' ||
         transactionType == 'y' )
    {
      continue ;
    }
  }
  {
    cout << "abcdefghijklmnopqr";
  }
}

Most of your program doesn't make any sense. Should I elaborate or do you wanna look at a newbie tutorial?

Last edited by iamthwee; Jun 22nd, 2008 at 4:04 pm.

*Voted best profile in the world*

•

Join Date: Jun 2008

Posts: 10

Reputation: Superfat is an unknown quantity at this point

Solved Threads: 0

Superfat

Offline

Newbie Poster

Re: Random number sequences

Jun 22nd, 2008

Elaborate please =], i was trying to say that a-r are random numbers between 1 and 9, this is just a snipet of some code i already have, i an just having some problems with figuring out random numbers... i figured that if the largest variable is an unsigned, max of about 4 billion, and seing as i need a 17 digit number, i generate a number for each digit, when the person continues it prints out each digit in the end

•

Join Date: Apr 2008

Posts: 296

Reputation: tesuji is on a distinguished road

Solved Threads: 42

tesuji

Offline

Posting Whiz in Training

Re: Random number sequences

Jun 22nd, 2008

•

Originally Posted by Superfat

Elaborate please =], i was trying to say that a-r are random numbers between 1 and 9, this is just a snipet of some code i already have, i an just having some problems with figuring out random numbers... i figured that if the largest variable is an unsigned, max of about 4 billion, and seing as i need a 17 digit number, i generate a number for each digit, when the person continues it prints out each digit in the end

Well dear Superfat, the most effective solution for you problem has already been given by vijayan121. Unfortunately you aren't able to understand his fine function. So GOD's advice should be seriously followed.

Btw, your nice random numbers a..r never contain 9, got it?

krs,
tesu

Last edited by tesuji; Jun 22nd, 2008 at 4:39 pm.