prime number prog. need help

This is a discussion on prime number prog. need help within the C Programming forums, part of the General Programming Boards category; heres the question You can use an array of bit-field structures as the problem states, or just a simple array ...

  1. #1
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    prime number prog. need help

    heres the question

    You can use an array of bit-field structures as the problem states, or just a simple array of int instead. Either way, in the loop which will go i=2..31999, use div() from stdlib.h to produce the array index and bit number, e.g. r = div(i,32); then r.quot is the array index and r.rem is the bit position (0...31).
    heres my code

    PHP Code:
    #include <stdio.h> 
    #include <stdlib.h> 
    int p[1000]; 
    int main(void

    int i,j
    int m,k
    div_t d
    for (
    =2i<300i++) 

        
    divi300); 
        
    d.rem
        
    d.quot
         
        if( (
    p[k] & (1<<m)) != 0) continue; 
        for( 
    2*i300+= i); p[k] |= ( 1<<); 
         
      } 
      for( 
    2300; ++i
      { 
        if( (
    p[k] && (1<<i)) == 0printf"%d\n"i); 
      } 
      return 
    0

    it compiles but its not printing anything?
    anyone know why?

  2. #2
    Gawking at stupidity
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    Code:
    if( (p[k] && (1<<i)) == 0) printf( "%d\n", i);
    Should that be a bitwise AND instead of a logical AND?
    If you understand what you're doing, you're not learning anything.

  3. #3
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    wow thanks.. that did it!

  4. #4
    and the hat of wrongness Salem's Avatar
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    > (1<<i)
    This isn't going to do anything meaningful for values of i past 31

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