Convert hexadecimal charArray to String

Question

I have a serious and irritating problem, please help

mdContext->digest[i] is an unsigned char Array with hexadecimal values so

for (i = 0; i < 16; i++)
    printf ("%02x", mdContext->digest[i]);

prints 900150983cd24fb0d6963f7d28e17f72

now.... I want to get this value in a char Array, i.e if I do

printf("%s",ArrayConverted);

I want to print the above string... Please help me in doing this

Things I tried

Trial-1

unsigned char in[64]=0;
  int tempValue[64];
 

  for (i = 0; i < 16; i++){
      sprintf(&tempValue[i],"%02x", (unsigned char)mdContext->digest[i]);
          in[i]=(unsigned char)tempValue[i];
  }
  
 printf("%s\n\n\n",in);

This prints 90593d4bd9372e77 But Original content is 900150983cd24fb0d6963f7d28e17f72

So it is skipping many characters in between... please help me converting this hexadecimal Char array in to a String

change tempValue to a `char` array, vice `int`, and see what you get. — mpez0, Mar 13 '11 at 01:16

Erik · Answer 1 · 2011-03-12T21:05:43.450

char tempValue[33]; // 32 hex digits + 0-terminator
int i;
for (i = 0; i < 16; ++i)
  sprintf(tempValue + 2*i, "%02x", (unsigned char)mdContext->digest[i]);

Each byte requires two hexadecimal digits - so adjust the start position for sprintf with 2*i

tempValue + 2*i is the same as &tempValue[2*i]

EDIT: A correct c++ version.

std::stringstream s;
for (int i = 0; i < 16; ++i) 
  s << std::hex << std::setfill('0') << std::setw(2) << (unsigned short) mdContext->digest[i];
std::cout << s.str() << std::endl;

Nawaz · Answer 2 · 2011-03-12T21:14:29.707

1

C++ specific solution:

    #include <sstream> 
    #include <iomanip>

    std::stringstream s;
    s.fill('0');
    for ( size_t i = 0 ; i < 16 ; ++i )
       s << std::setw(2) << std::hex <<(unsigned short)mdContext->digest[i]);
    std::cout << s.str() << endl;

Small demo : http://ideone.com/sTiEn

edited Mar 12 '11 at 21:14

answered Mar 12 '11 at 20:56

Nawaz

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@Erik: Updated. See if it's fixed now. – Nawaz Mar 12 '11 at 21:08
@Nawaz: Don't you just hate streams :P - I'll remove comments now, please add the setfill as well – Erik Mar 12 '11 at 21:11
@Erik: Oops. Fixed that as well :D. BTW, why did you say "don't you just hate streams"? :-/ – Nawaz Mar 12 '11 at 21:14
1

@Nawaz: Don't everyone hate streams? I mean, **look** at the syntax for simple printing of hex values... I'm usually very fond of C++ constructs, but the streams are, well, not the most clever part of the stdlib :P – Erik Mar 12 '11 at 21:17
@Erik: Yeah. Here it looks ugly. But sometimes it's really very smart. For example see the SECOND solution here in my post : http://stackoverflow.com/questions/4888879/elegant-ways-to-count-the-frequency-of-words-in-a-file/4888916#4888916 – Nawaz Mar 12 '11 at 21:19
@Nawaz: I usually use streams for debug logging, i like the type safety. But sometimes sprintf just beats everything else :) – Erik Mar 12 '11 at 21:23
@Erik: Do you think sprintf family can beat stream in the link I gave you? – Nawaz Mar 12 '11 at 21:25
@Nawaz: hehe no. Streams can be used for lots of clever things, but formatting isn't one of them :) – Erik Mar 12 '11 at 21:26
@Erik: Yeah. True. When it comes to formatting, printf-family beat streams. But once in while I try using stringstream so I don't forget how to use it; that means, this solution is not only for others, but for me as well :D – Nawaz Mar 12 '11 at 21:31

Convert hexadecimal charArray to String

Trial-1

2 Answers2