#include <stdio.h>

              #include <openssl/bio.h>

                    

              int     main()

              {

                            BIO     *b=NULL;

                            int     len=0,outlen=0;

                         char    *out=NULL;

                    

                         b=BIO_new_file("bf.txt","w");

                         len=BIO_write(b,"openssl",4);

len=BIO_printf(b,"%s","zcp");

                            BIO_free(b);  

                            b=BIO_new_file("bf.txt","r");

                            len=BIO_pending(b);

                            len=50;

                            out=(char *)OPENSSL_malloc(len);

                            len=1;

                            while(len>0)

                            {    

                                   len=BIO_read(b,out+outlen,1);

                                   outlen+=len;

                            }

                            BIO_free(b);

                            free(out);

                         return 0;

                     }