Your problem is that you're calling printf on a static char array. If
you're going to use printf you have to use it on the .ptr (pointer)
field of the static array. Replace this call:
printf("Connection error: %s\n", c.errstr);
with
printf("Connection error: %s\n", c.errstr.ptr);
On my end I get:
Connection error: Connection refused
Also I think you should replace the "int integer" in struct redisReply
to "long integer". I think `long long` in C is 8 bytes, which is the
equivalent to D's long type.
