簡易ntop実装

ntop.c

#include <string.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>

/*
https://code.woboq.org/userspace/glibc/resolv/inet_ntop.c.html#15tmp
*/

void ip_ntop(uint32_t src, char *dest){

        u_char addr[16];
        sprintf(addr,"%u.%u.%u.%u",(src >>  0) & 0xFF,(src >>  8) & 0xFF,(src >>  16) & 0xFF,(src >>  24) & 0xFF);
        strcpy(dest, addr);
}

int main(int argc, char *argv[]){

uint32_t address = 2600511680; //IP 想定

char ip[16];

ip_ntop(address, ip);

printf("%s\n", ip);

return 0;
}

/*
printf("%ld", sizeof "255.255.255.255");
結果
16

255.255.255.255 は 16バイト 
*/

$ ./a.out 
192.168.0.155