Can't print gmp variable

I'm working on a project that required gmp and mpz_t. When I try to print the object to either a file or the io my app crashes with the message:

Detected an attempt to call a symbol in system libraries that is not present on the iPhone: fwrite$UNIX2003 called from function __gmpz_out_str in image libgmp.3.dylib. If you are encountering this problem running a simulator binary within gdb, make sure you 'set start-with-shell off' first.

This is my code:

mpz_out_str(stdout, 10, d); gmp_printf("d is %Zd", d);

both crash. All I want to do is to print my varia开发者_运维百科bles.