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converting to 32 bit long form

Discussion in 'C' started by arvind_khadri, Nov 16, 2007.

  1. arvind_khadri

    arvind_khadri New Member

    hi...hey guys i just wanted a help on this....how do i convert a given number to a 32 bit long form...plz help....
     
  2. Salem

    Salem New Member

    Do you have any examples of what you're trying to accomplish?
     
  3. arvind_khadri

    arvind_khadri New Member

    if i enter 153.18.8.105 the o/p should be 2568095849....for separation u can use strtok for separating.....
     
  4. Salem

    Salem New Member

    Use strtol().
    One of the things it returns is a pointer to where it got to (ie, the dots between numbers).
    This you use to locate the start of the next number.
     
  5. arvind_khadri

    arvind_khadri New Member

    well salem i got tat part...but the next thing is how do i convert...tats wat am nt able to get...so i needed help on it.....
     
  6. Salem

    Salem New Member

    You mean that
    2568095849 is (153 << 24) + (18 << 16) + (8 << 8) + 105

    It's just a loop, with a shift and and add.
     
  7. arvind_khadri

    arvind_khadri New Member

    thanks for tat...well so rt nw u mean to say tat find the binary eqvt and keep shifting and then concatenate the thing to find final result??if u could post the code here it would be really very helpful of u...
     
  8. arvind_khadri

    arvind_khadri New Member

    i wasnt able to sihft it...whenver i giver 153<<24 it shows 0 as o/p....
     
  9. Salem

    Salem New Member

    Well it would do, if you were storing the result in an unsigned char say. All the bits fell off the end!

    It needs to be in an unsigned long before you shift it left 24 bits.
     
  10. arvind_khadri

    arvind_khadri New Member

    i could get the following code...but cant understand how it works.....can u pls explain it....
    code:cpp

    Code:
    #include<string.h>
    #include<conio.h>
    #include<stdio.h>
    #include<math.h>
    union ipadd
     {
     unsigned long int a;
     } e;
    void main()
    {
    char ip[100];
    char *p;
    int i,n,j,po;
    unsigned long int d;
    e.a=0;
    clrscr();
    printf("\nenter the ip");
    scanf("%s",ip);
    p=strtok(ip,".");
    n=strlen(p) ;
    d=0;
    po=0;
    for(i=n-1;i>=0;i--)
     {
     d=d+(*(p+i)-48)*pow(10,po);
     po++;
     }
    e.a=d*pow(256,3);
    for(j=2;j>=0;j--)
     {
      p=strtok(NULL,".");
      n=strlen(p);
      d=0;
      po=0;
      for(i=n-1;i>=0;i--)
        {
         d=d+(*(p+i)-48)*pow(10,po);
         po++;
        }
      e.a=e.a+d*pow(256,j);
      }
    printf("\n the ip add is :%lu",e.a);
    getch();
    }
     
    Last edited by a moderator: Nov 18, 2007
  11. Salem

    Salem New Member

    I could, but I'm not interested in reading code which has been posted without using code tags.
     
  12. shabbir

    shabbir Administrator Staff Member

    arvind_khadri, Learn to post code in the posts with the code block
     
  13. arvind_khadri

    arvind_khadri New Member

    shabbir thanks for the code block....
    now its in code block...now pls help me....
     
  14. Salem

    Salem New Member

    Sure, there are lots of things wrong with it.

    > void main()
    http://c-faq.com/ansi/voidmain.html

    > #include<conio.h>
    This is a non-standard header file, so you should avoid using unless necessary.
    It is also obsolete as well, as no new compiler will ever have such a thing. Even compilers like dev-c++ which do include it do only for backward compatibility.

    > union ipadd
    A union with only one member is kinda pointless, so it looks just like a struct.

    > d=d+(*(p+i)-48)*pow(10,po);
    You know, this is exactly what strtol() does, so why not use it?
    In fact using strtol() means you can avoid the messy strtok() function as well, which as a side-effect trashes the input string.
     

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