c++ - 如何在c或c++中循环生成随机256位十六进制？

Question

在Python中我这样做:

import random

while True:
    x = random.randint(0xF,0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364140)
    print hex(x)[2:66].lower()

如何使用 C 或 C++ 做到这一点？

Answer 1

使用GNU MP library ，这可以这样完成:

#include <stdio.h>
#include <ctype.h>
#include <gmp.h>

void randint(mpz_t rop, gmp_randstate_t state, mpz_t from, mpz_t to) {
    mpz_t range;
    mpz_init(range);
    /* range = to - from + 1 */
    mpz_sub(range, to, from);
    mpz_add_ui(range, range, 1);
    /* rop = random number in [0, range) */
    mpz_urandomm(rop, state, range);
    /* rop += from */
    mpz_add(rop, rop, from);
    mpz_clear(range);
}

int main(void) {
    char str[1024]; /* allocate enough memory */
    gmp_randstate_t state;
    mpz_t low, high;
    mpz_t ret;
    gmp_randinit_default(state);
    mpz_init(ret);

    mpz_init_set_str(low, "F", 16);
    mpz_init_set_str(high, "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364140", 16);
    for(;;) {
        randint(ret, state, low, high);
        str[0]='0'; str[1]='x';
        mpz_get_str(str + 2, 16, ret);
        if (str[0] != '\0' && str[1] != '\0') {
            int i;
            for (i = 2; i < 66 && str[i] != '\0'; i++) putchar(tolower(str[i]));
        }
        putchar('\n');
    }
    /* the control won't come here */
#if 0
    mpz_clear(low);
    mpz_clear(high);
    mpz_clear(ret);
    gmp_randclear(state);
    return 0;
#endif
}