mpz_print function defined in mpz.h is not working

[mariay201093]

In kernel.cu, if I add a printf statement for example printf("\nHello") it works properly. But if I want to print the value of any variable like op1, op2 or sum used in kernel.cu, it does not give the output on the console.
I referred the mpz.h file and found a mpz_print(mpz_t *mpz) function defined in it but that too does not work.
I want to know the value of variable sum after the computation in gpu and hence require the printf statement. Can you please help me with this issue.