void print_same_subnet(const ipaddr_t addr_array_1[], const ipaddr_t addr_array_2[], int addr_array_len)
{
    for(i=0; i < addr_array_len; i++)
    {
        if(is_same_subnet(addr_array_1[i], addr_array_2[i]))
        {
            //Do what you want here
        } 
    }
}

如果您不介意数组被更改，一种方法是对地址进行排序，以便将它们分组在一起，从而可以更容易地作为一个组输出：

#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>

struct ipaddr{
    int octet1;
    int octet2;
    int octet3;
    int octet4;
};
typedef struct ipaddr ipaddr_t;

int compare_ips (const ipaddr_t *ip1, const ipaddr_t *ip2) {
    if (ip1->octet1 != ip2->octet1) return ip1->octet1 - ip2->octet1;
    if (ip1->octet2 != ip2->octet2) return ip1->octet2 - ip2->octet2;
    if (ip1->octet3 != ip2->octet3) return ip1->octet3 - ip2->octet3;
    return ip1->octet4 - ip2->octet4;
}
typedef int (*qsort_comparator)(const void *, const void*);

int is_same_subnet(ipaddr_t ip1, ipaddr_t ip2){
    return (ip1.octet1 == ip2.octet1 &&
            ip1.octet2 == ip2.octet2 &&
            ip1.octet3 == ip2.octet3);
}

void print_same_subnet(ipaddr_t addr_array[], int addr_array_len){
    qsort (addr_array, addr_array_len, sizeof (ipaddr_t), (qsort_comparator) compare_ips);
    bool fresh_match = true;
    for (int i = 0; i < addr_array_len - 1; i++) {
        if (is_same_subnet (addr_array[i], addr_array[i+1])) {
          if (fresh_match) {
            printf("%i.%i.%i.%i ", addr_array[i].octet1, addr_array[i].octet2, addr_array[i].octet3, addr_array[i].octet4);
            fresh_match = false;
          }
          printf("%i.%i.%i.%i ", addr_array[i+1].octet1, addr_array[i+1].octet2, addr_array[i+1].octet3, addr_array[i+1].octet4);
        } else {
            if (!fresh_match) {
                printf ("\n");
            }
            fresh_match = true;
        }
    }
    if (!fresh_match) {
        printf ("\n");
    }
}

int main (void) {
    struct ipaddr addr_array[] = {
            { 10, 32, 39, 49 },
            { 10, 32, 25, 95 },
            { 10, 32, 39, 27 },
            { 10, 32, 39, 88 },
            { 10, 32, 25, 22 },
            { 10, 99, 25, 22 },
    };

    print_same_subnet (addr_array, 6);
}

一个简单的方法是构建一个相同大小的辅助数组来记录已经处理了哪些地址。代码可以是（或多或少）：

void print_same_subnet(const ipaddr_t addr_array[], int addr_array_len){
    int i, k;
    int *seen = malloc(addr_array_len * sizeof(int)); // allocate auxilliary array
    for(i=0; i<addr_array_len; i++) seen[i] = 0;      // and set it to 0
    for(i=0; i < addr_array_len; i++){
        if (seen[i]) continue;                        // do not process twice the same row
        printf("%i.%i.%i.%i", addr_array[i].octet1, addr_array[i].octet2,
        addr_array[i].octet3, addr_array[i].octet4);
        for(k=i+1; k < addr_array_len; k++){          // search all addresses sharing same network
            if (seen[k]) continue;                    // ignore already seen addresses
            if (is_same_subnet(addr_array[i], addr_array[k])) {
                seen[k] = 1;                          // note it
                printf(" %i.%i.%i.%i", addr_array[k].octet1,   // and display it on same line
                addr_array[k].octet2, addr_array[k].octet3, addr_array[k].octet4);
            }
        }
        printf("\n");
    }
    free(seen);          // free the auxilliary array
}