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From: dkeisen@Gang-of-Four.Stanford.EDU (Dave Eisen)
Newsgroups: comp.lang.c
Subject: Re: Converting ascii hex values to hex bytes
Message-ID: <1990Oct17.162529.20096@Neon.Stanford.EDU>
Date: 17 Oct 90 16:25:29 GMT
References: <298@cti1.UUCP>
Sender: news@Neon.Stanford.EDU (USENET News System)
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Lines: 39

In article <298@cti1.UUCP> mpledger@cti1.UUCP (Mark Pledger) writes:
>and fwrite() to get a lot of different configuration data.  What I want to 
>do is to be able to convert 122.10.10.44 into a character string of 4 bytes
>that equals "\x7a\x0a\x0a\x2c".  How can I convert the ascii representation
>into hex?  I tried using itoa(), but the result is in ascii character format

You don't want to convert anything into hex, you want to convert the
character string "122.10.10.44" into four one-byte integers, char
being a synonym for one-byte integers. Something like this 
will do it:

int
convert_data (const char *ascii, char *four_bytes)
{
  char *p;
  int bytenum;

  for (bytenum = 0, p = ascii; bytenum < 4; bytenum++)
    {
      four_bytes[bytenum] = atoi (p);
      if ((p = strchr (p, '.')) == NULL)   /* strchr is called index in BSD */
        return -1;
    }

  return 0;
}


Hex is only meaningful when you go to output the four bytes of data and
you need to convert it into a hex string.




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Dave Eisen                      	    Home: (415) 323-9757
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