random number

[José de Jesús Angel Angel]

Hello

I would like know if this is the best way for generating a randon number 
of  160 bits.
What I have to do for improve this.

 unsigned long int  seed;
 mpz_t  temp;
 gmp_randstate_t state;
 mpz_init(temp);
 gmp_randinit_default(state);
 
 seed= rand();
 gmp_randseed_ui (state,seed);
 

mpz_urandomb(temp, state, 160);
mpz_out_str (NULL, 10, temp);
cout << endl;

mpz_clear(temp);