same random number again

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Hi,

I have made this random program but I am keep getting the same answer as 41. Any help to get a random number between 1 to 100 each time I run the program rather then 41 only.

C++

void main()
{
	int userData;
	int random;

	printf("\t\t\t Lotto Game \n");
	printf("\t\t\t ---------- \n\n");
	printf("Enter a number to see if you have win a price : ");
	scanf("%d%*c",&userData);
	random = rand() ;
	
	if (userData > random)
	{
		printf("Your entry is higher\n");

	}

	else if (userData < random)
	{
		printf("Your entry is lower\n");
	}

	else 
	{
		printf("Corrent answer, you are a winner :-)\n");
	}

	printf("Correct answer is %d \n",random);


	system("pause\n");

}

Posted 7-Jul-12 5:40am

Salman Ali Hero

Updated 7-Jul-12 5:45am

André Kraak

v2

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Comments

Sergey Alexandrovich Kryukov 7-Jul-12 11:52am

Are you writing a computer game for mentally retarded children? :-)
--SA

Salman Ali Hero 12-Jul-12 1:15am

ha ha ha, I am thinking to upload this app on Itunes and make $$lol

3 solutions

Solution 3

Randomize (seed) the pseudo-random number generator using srand, as shown in the code sample below:
http://www.cplusplus.com/reference/clibrary/cstdlib/rand/[^].

Do it only once per run time!

—SA

Posted 7-Jul-12 5:55am

Sergey Alexandrovich Kryukov

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Richard MacCutchan · Accepted Answer · 2012-07-07T05:52:00

Solution 1

Since you are only doing this once in your program it will generally return the same number. You need to seed the randomiser via the srand()[^] function, using a seed value that is unique, something like the current time would be a reasonable choice.

Posted 7-Jul-12 5:52am

Richard MacCutchan

Comments

Salman Ali Hero 7-Jul-12 12:05pm

Thanks, solved my problem

André Kraak · Accepted Answer · 2012-07-07T05:53:00

As you can read from this[^] you need to initialize the random number generator (using the srand function[^]) before calling the rand function it.

Example from the reference link:

C++

/* rand example: guess the number */
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main ()
{
  int iSecret, iGuess;

  /* initialize random seed: */
  srand ( time(NULL) );

  /* generate secret number: */
  iSecret = rand() % 10 + 1;

  do {
    printf ("Guess the number (1 to 10): ");
    scanf ("%d",&iGuess);
    if (iSecret<iGuess) puts ("The secret number is lower");
    else if (iSecret>iGuess) puts ("The secret number is higher");
  } while (iSecret!=iGuess);

  puts ("Congratulations!");
  return 0;
}