title: getting fatal error when using this header <openssl/md5.h>
body: <p>im getting this error when i run this code 
  fatal error: openssl/md5.h: No such file or directory
  i had already installed openssl but still get this error 
  all answers are for linux users i'm using windows.</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  #include &lt;stdlib.h&gt;
  #include &lt;string.h&gt;
  #if defined(__APPLE__)
  #  define COMMON_DIGEST_FOR_OPENSSL
  #  include &lt;CommonCrypto/CommonDigest.h&gt;
  #  define SHA1 CC_SHA1
  #else
  #  include &lt;openssl/md5.h&gt;
  #endif
  
  char *str2md5(const char *str, int length) {
     int n;
     MD5_CTX c;
     unsigned char digest[16];
     char *out = (char*)malloc(33);
  
     MD5_Init(&amp;c);
  
     while (length &gt; 0) {
          if (length &gt; 512) {
              MD5_Update(&amp;c, str, 512);
          } else {
              MD5_Update(&amp;c, str, length);
          }
          length -= 512;
          str += 512;
       }
  
       MD5_Final(digest, &amp;c);
  
       for (n = 0; n &lt; 16; ++n) {
       snprintf(&amp;(out[n*2]), 16*2, "%02x", (unsigned int)digest[n]);
       }
  
      return out;
   }
  
     int main(int argc, char **argv) {
         char *output = str2md5("hello", strlen("hello"));
         printf("%s\n", output);
         free(output);
          return 0;
      }
  </code></pre>