How to convert an integer array into an ip address in c++? [closed]

Answer 1

One way is:

char buf[16];
snprintf( buf, sizeof buf, "%d.%d.%d.%d",
    ipAddress[0], ipAddress[1], ipAddress[2], ipAddress[3] );

Personally I find this more elegant than 10-line solutions involving loops and multiple function calls, others will disagree!

Answer 2

If you want to convert it using inet_ntoa() as you mentioned you can do:

int main() {
    struct in_addr addr;
    char* some_addr;
    int ipAddress[] = {127,0,0,1};

    addr.s_addr = (ipAddress[3] << 24) | (ipAddress[2] << 16) | (ipAddress[1] << 8) | ipAddress[0];
    some_addr = inet_ntoa(addr);
    printf("%s\n", some_addr);

    return 0;
}

Test

EDIT: The main post has been edited, but the original stated he tried using the inet_ntoa() method for this.

Answer 3

Just roll your own by looping through the array and adding the integers where needed:

constexpr int ipvals[] = {127, 0, 0, 1};
constexpr size_t size_vals = sizeof(ipvals) / sizeof(*ipvals);
std::ostringstream ss;
for(int i = 0; i < size_vals; ++i)
{
    ss << ipvals[i];
    if(i != size_vals - 1)
      ss << '.';
}

Example

Answer 4

You can always use to_string() method:

#include<string>
#include<iostream> 

using namespace std;

int main() {
    string s;
    int ipAddress[] = {127, 0, 0, 1};
    for(int i = 0; i < 4; ++i) {
        s += to_string(ipAddress[i]);
        if(i != 4 - 1)
            s += '.';
    }
    cout << s << endl;
}

This will solve your problem

Answer 5

Edit of M.M's answer to make a C/C++ function specific for IPv4 addresses; forcing use of valid address input and buffer length for output:

bool ipv4_addr_to_str(uint8_t (*ipv4_addr)[4], char (*str)[16])
{
    bool success = false;
    if (ipv4_addr != NULL && str != NULL)
    {
        memset(*str, 0, 16);
        snprintf(*str, sizeof(*str), "%d.%d.%d.%d", 
                (*ipv4_addr)[0], (*ipv4_addr)[1], (*ipv4_addr)[2], (*ipv4_addr)[3]);
        success = true;
    }
    return success;
}