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Re: convert unsigned long long into char[4]

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On 11/25/2015 12:23 AM, Malcolm McLean wrote:
> On Tuesday, November 24, 2015 at 11:40:48 PM UTC, bilsch01 wrote:
>> See the code below.  The function d2hx takes a 4 digit hex number 0xfffe
>> and converts it into ascii bytes returned in unsigned long long
>> 'answer'.  The contents of answer is 0x46464645
>> where 0x46 = 'F' and 0x45 = 'E'
>> In the C code below I need to convert 'answer' into type char[4] (plus
>> null termination will be char[5]) and print it with printf.  The result
>> will be FFFE  I don't know how to convert unsigned long long into char[4].
>>
>> TIA.    Bill S.
>>
>>
>> #include  <stdio.h>
>>
>> extern unsigned long long d2hx(int dec);
>>
>> int main(){
>> int dc = 0xfffe;
>> unsigned long long answer;
>>
>> answer = d2hx(dc);
>> printf("answer = %s\n", answer);
>> return 0;
>> }
>
>
> unsigned long long d2hx(int dc)
> {
>    char hex[5];
>    int i;
>    unsigned long long answer = 0;
>    assert(dc >= 0 && dc <= 0xFFFF);
>
>    for(i=0;i<4;i++)
>    {
>      hex[i] = "0123456789abcdef"[(dc >> ((3-i) * 4)) & 0xF];

I've never seen:  "character list"[bitwise and]
I realize what is intended but I've never seen the two things interact 
like that.
>    }
>    hex[i] = 0;
>    memcpy(&answer, hex, 5);
>
>    return answer;
> }
>
>   int main(){
>    int dc = 0xfffe;
>    unsigned long long answer;
>
>   answer = d2hx(dc);
>   // bug here, add the &
>   printf("answer = %s\n", &answer);
>   return 0;
> }
>

Thanks.

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convert unsigned long long into char[4] bilsch01 <king621@comcast.net> - 2015-11-24 15:40 -0800
  Re: convert unsigned long long into char[4] Barry Schwarz <schwarzb@dqel.com> - 2015-11-24 17:21 -0800
    Re: convert unsigned long long into char[4] bilsch01 <king621@comcast.net> - 2015-11-24 18:10 -0800
      Re: convert unsigned long long into char[4] Keith Thompson <kst-u@mib.org> - 2015-11-24 18:18 -0800
  Re: convert unsigned long long into char[4] Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-25 00:23 -0800
    Re: convert unsigned long long into char[4] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-25 11:54 +0000
    Re: convert unsigned long long into char[4] bilsch01 <king621@comcast.net> - 2015-11-25 11:35 -0800
  Re: convert unsigned long long into char[4] Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-11-28 22:06 +0000

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