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Prime numbers..problem with code

Discussion in 'C' started by zeeshan, Dec 1, 2006.

  1. zeeshan

    zeeshan New Member

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    hi friends, im a newbie at C,

    im trying to code for a program which cud return all prime numbers in a specific range.

    its returning the results with an error, which is , it also includes the products of two prime numbers in results,
    for example 15=3*5 and 21=3*7

    my code is
    ---------------------------------------------------------
    Code:
    #include<conio.h>
    #include<stdio.h>
    void main()
    {
    clrscr();
    for (int i=1;i<=300;i++)
     {
      for(int j=2;j<=i;j++)
       if(i%j==0 )
    
       break;
       else
           {
    	printf("\t%d ",i);
    	break;
    	}
      }
    getche();
    }
    --------------------------------------------------
    Result:

    3 5 7 9 11 13 15 17 19 21 23 .................

    kindly guide me where the problem resides.
    which is letting 15,21 etc in output.
     
    Last edited by a moderator: Dec 4, 2006
  2. pradeep

    pradeep Team Leader

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    Here is the code for finding a prime number in a specified range.

    Code:
    #include <stdio.h>
    #include <math.h>
    // The range of numbers where you want to look for prime numbers
    #define RANGE_MIN 2
    #define RANGE_MAX 100
    
    void main(void)
    {
        int i,j,sq,is_prime;
    
        for(i=RANGE_MIN;i<=RANGE_MAX;i++)
        {
    
            is_prime = 1;
            sq = sqrt(i); // calculate the square root
            for(j=2;j<=sq;j++)
            {
                if(i%j==0)
                    is_prime = 0;
            }
    
            if(is_prime)
                printf("%d, ",i);
        }
    }
    Also checkout this thread http://www.go4expert.com/showthread.php?t=2049
     
  3. friendsforniraj

    friendsforniraj New Member

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    thats great now
     

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