Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c > #150966

Re: Portable way of reading str[4] as uint32_t

Show all headers | View raw

Spiros Bousbouras <spibou@gmail.com> writes:

> On Mon, 30 Mar 2020 23:28:33 -0700 (PDT)
> wyniijj@gmail.com wrote:
>
>> Richard Damon
>>
>>> On 3/30/20 2:42 PM, wyniijj@gmail.com wrote:
>>>
>>>> I'd like to read the value a.value in the following program as
>>>> 0x78563412 in a portable way, none of hton or ntoh is useful.
>>>> How should I do?
>>>>
>>>> #include <stdio.h>
>>>> #include <arpa/inet.h>
>>>>
>>>> int main()
>>>> {
>>>>  union {
>>>>    char str[4];
>>>>    uint32_t value;
>>>>  } a;
>>>>
>>>>  a.str[0]=0x12;
>>>>  a.str[1]=0x34;
>>>>  a.str[2]=0x56;
>>>>  a.str[3]=0x78;
>>>>
>>>>  printf("host= %08x\n",a.value);
>>>>  printf("hton= %08x\n",htonl(a.value));
>>>>  printf("ntoh= %08x\n",ntohl(a.value));
>>>>  return 0;
>>>> }

[...]

> I note also that to have  uint32_t  you need
> #include <stdint.h>

Actually not, because <arpa/inet.h> was already #include'd.
See for example the man page for htonl().

Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Protable way of reading str[4] as uint32_t wyniijj@gmail.com - 2020-03-30 11:42 -0700
  Re: Protable way of reading str[4] as uint32_t Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-03-30 20:14 +0100
    Re: Protable way of reading str[4] as uint32_t Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-03-30 20:11 +0000
  Re: Protable way of reading str[4] as uint32_t Richard Damon <Richard@Damon-Family.org> - 2020-03-30 20:04 -0400
    Re: Protable way of reading str[4] as uint32_t Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-03-30 19:04 -0700
      Re: Protable way of reading str[4] as uint32_t wyniijj@gmail.com - 2020-03-30 23:30 -0700
        Re: Protable way of reading str[4] as uint32_t Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-03-31 10:59 -0700
          Re: Protable way of reading str[4] as uint32_t Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-03-31 12:19 -0700
            Re: Protable way of reading str[4] as uint32_t wyniijj@gmail.com - 2020-04-01 06:37 -0700
    Re: Protable way of reading str[4] as uint32_t wyniijj@gmail.com - 2020-03-30 23:28 -0700
      Re: Portable way of reading str[4] as uint32_t Spiros Bousbouras <spibou@gmail.com> - 2020-03-31 11:29 +0000
        Re: Portable way of reading str[4] as uint32_t wyniijj@gmail.com - 2020-03-31 09:59 -0700
          Re: Portable way of reading str[4] as uint32_t Spiros Bousbouras <spibou@gmail.com> - 2020-03-31 18:03 +0000
        Re: Portable way of reading str[4] as uint32_t Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-02 19:09 -0700
          Re: Portable way of reading str[4] as uint32_t Spiros Bousbouras <spibou@gmail.com> - 2020-04-03 05:02 +0000
            Re: Portable way of reading str[4] as uint32_t James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-03 01:10 -0400
              Re: Portable way of reading str[4] as uint32_t gazelle@shell.xmission.com (Kenny McCormack) - 2020-04-03 08:18 +0000
              Re: Portable way of reading str[4] as uint32_t Spiros Bousbouras <spibou@gmail.com> - 2020-04-03 09:48 +0000
                Re: Portable way of reading str[4] as uint32_t gazelle@shell.xmission.com (Kenny McCormack) - 2020-04-03 11:07 +0000
            Re: Portable way of reading str[4] as uint32_t BGB <cr88192@gmail.com> - 2020-04-03 09:41 -0500
              Re: Portable way of reading str[4] as uint32_t Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-03 07:51 -0700
                Re: Portable way of reading str[4] as uint32_t Richard Damon <Richard@Damon-Family.org> - 2020-04-03 12:09 -0400
                Re: Portable way of reading str[4] as uint32_t BGB <cr88192@gmail.com> - 2020-04-03 13:19 -0500
                Re: Portable way of reading str[4] as uint32_t James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-03 14:52 -0400
                Re: Portable way of reading str[4] as uint32_t Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-03 12:10 -0700
                Re: Portable way of reading str[4] as uint32_t BGB <cr88192@gmail.com> - 2020-04-03 15:17 -0500
                Re: Portable way of reading str[4] as uint32_t James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-03 23:39 -0400
                Re: Portable way of reading str[4] as uint32_t Spiros Bousbouras <spibou@gmail.com> - 2020-04-03 21:28 +0000
            Re: Portable way of reading str[4] as uint32_t Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-04 19:28 -0700
      Re: Protable way of reading str[4] as uint32_t Richard Damon <Richard@Damon-Family.org> - 2020-03-31 08:05 -0400
        Re: Protable way of reading str[4] as uint32_t BGB <cr88192@gmail.com> - 2020-03-31 09:12 -0500
          Re: Protable way of reading str[4] as uint32_t Philipp Klaus Krause <pkk@spth.de> - 2020-03-31 17:27 +0200
            Re: Protable way of reading str[4] as uint32_t BGB <cr88192@gmail.com> - 2020-03-31 18:26 -0500
              Re: Protable way of reading str[4] as uint32_t Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-04-01 06:03 +0000
                Re: Protable way of reading str[4] as uint32_t Richard Damon <Richard@Damon-Family.org> - 2020-04-01 08:17 -0400
                Re: Protable way of reading str[4] as uint32_t James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-01 09:57 -0400
                Re: Protable way of reading str[4] as uint32_t BGB <cr88192@gmail.com> - 2020-04-01 09:47 -0500
                Re: Protable way of reading str[4] as uint32_t James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-01 11:48 -0400
                Re: Protable way of reading str[4] as uint32_t BGB <cr88192@gmail.com> - 2020-04-01 12:37 -0500
      Re: Protable way of reading str[4] as uint32_t James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-03-31 12:56 -0400

csiph-web