EVP_Digest Example Compile Errors

[mmdonley]

MacBook 2,1 Mac OS X 10.7.4 Xcode 4.3.3

MacPorts    openssl @1.0.1c_0 (active)


When I attempt to compile the example at

http://www.openssl.org/docs/crypto/EVP_DigestInit.html

using

gcc -Wall -I /opt/local/include -o mdtest mdtest.c 

I get the following errors from gcc:

Undefined symbols for architecture x86_64:
  "_OpenSSL_add_all_digests", referenced from:
      _main in cc2OLVyU.o
  "_EVP_get_digestbyname", referenced from:
      _main in cc2OLVyU.o
  "_EVP_MD_CTX_create", referenced from:
      _main in cc2OLVyU.o
  "_EVP_DigestInit_ex", referenced from:
      _main in cc2OLVyU.o
  "_EVP_DigestUpdate", referenced from:
      _main in cc2OLVyU.o
  "_EVP_DigestFinal_ex", referenced from:
      _main in cc2OLVyU.o
  "_EVP_MD_CTX_destroy", referenced from:
      _main in cc2OLVyU.o
ld: symbol(s) not found for architecture x86_64
collect2: ld returned 1 exit status

When I grep for EVP_MD_CTX_create in /opt/local/include/openssl/evp.h
it is found,  but not with the leading underscore, the same is true for
the other "undefined symbols" above.

I have tried changing architecture to i386 and compiler
to cc, but results are the same.

Any info would be appreciated.

Thanks,
mmdonley
==================================================
The example to which I refer is included herein. Two minor
revisions were necessary: (1) include string.h and (2) change
md_len to an unsigned int:

#include <stdio.h>
#include <string.h>
#include <openssl/evp.h>

int main(int argc, char *argv[])
{
 EVP_MD_CTX *mdctx;
 const EVP_MD *md;
 char mess1[] = "Test Message\n";
 char mess2[] = "Hello World\n";
 unsigned char md_value[EVP_MAX_MD_SIZE];
 unsigned md_len, i;
 OpenSSL_add_all_digests();
 if(!argv[1]) {
        printf("Usage: mdtest digestname\n");
        exit(1);
 }
 md = EVP_get_digestbyname(argv[1]);
 if(!md) {
        printf("Unknown message digest %s\n", argv[1]);
        exit(1);
 }
 mdctx = EVP_MD_CTX_create();
 EVP_DigestInit_ex(mdctx, md, NULL);
 EVP_DigestUpdate(mdctx, mess1, strlen(mess1));
 EVP_DigestUpdate(mdctx, mess2, strlen(mess2));
 EVP_DigestFinal_ex(mdctx, md_value, &md_len);
 EVP_MD_CTX_destroy(mdctx);
 printf("Digest is: ");
 for(i = 0; i < md_len; i++) printf("%02x", md_value[i]);
 printf("\n");

 return 0;
}