title: can't find openssl/evp.h when I compile openssl_aes.c with gcc
body: <p>OK,I have install openssl-1.0.1e and I want to complier an program about AES,like this
  <a href="http://saju.net.in/code/misc/openssl_aes.c.txt" rel="nofollow">http://saju.net.in/code/misc/openssl_aes.c.txt</a></p>
  
  <p>the document prompt what I should input to complier</p>
  
  <p><strong>gcc -Wall openssl_aes.c -lcrypto</strong></p>
  
  <p>howerver there is an error:</p>
  
  <p><strong>openssl_aes.c:13:25: *<em>fatal error: openssl/evp.h: No such file or directory
  compilation terminated.</em>*</strong></p>
  
  <p>So what should I do？</p>