Copy hex values with sprintf in C

From the code below I am trying to get the result of the result var into a string var but no success so far. What's wrong? Why I can't get the right result? If I print this directly it's ok...

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/md5.h>

char *string = "stelios";
unsigned char s[MD5_DIGEST_LENGTH];
int main()
{
 int i;
 unsigned char result[MD5_DIGEST_LENGTH];

  MD5(string, strlen(string), result);

  // output
  for(i = 0; i < MD5_DIGEST_LENGTH; i++){
   sprintf(s,"%0x", result[i]);//
   printf("%x",s[i]);
  }
 开发者_如何学JAVA  printf("\n%x",s);

   return EXIT_SUCCESS;
  }

Try this:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/md5.h>

char *string = "stelios";
char s[MD5_DIGEST_LENGTH * 2 + 1] = "";
int main()
{
  int i;
  unsigned char result[MD5_DIGEST_LENGTH];

  MD5(string, strlen(string), result);

  // output
  for(i = 0; i < MD5_DIGEST_LENGTH; i++){
    char temp[3];
    sprintf(temp, "%02x", result[i]);
    strcat(s, temp);
  }
  printf("Final Hex String: %s",s);

  return EXIT_SUCCESS;
}

Each time sprintf is called, it writes the formatted value to the beginning of s, overwriting whatever was written there in the previous call. You need to do something like sprintf(s + i*2, "%02x", result[i]); (and change the length of s to 2*MD5_DIGEST_LENGTH+1).

Here's what I've used:

  char *digit="0123456789abcdef";
  char hex[2*MD5_DIGEST_LENGTH+1],*h;
  int i;
  for (h=hex,i=0; i<N; i++)
  {
   *h++=digit[digest[i] >> 4];
   *h++=digit[digest[i] & 0x0F];
  }
  *h='\0';