inet_ntoa

Converts an IPv4 network address structure to a string in standard dot-decimal notation.

Syntax

char *inet_ntoa(
  struct in_addr InAddress
);
        

Parameters

• InAddress: struct in_addr A structure that contains an IPv4 network address in network byte order.

Return Value

• If the function succeeds, the return value is a pointer to a statically allocated buffer containing the dot-decimal string representation of the IP address. Note: This buffer is not thread-safe and can be overwritten by subsequent calls to the same function.
• If the function fails, the return value is NULL.

Remarks

The inet_ntoa function converts an IPv4 address, stored in network byte order in an in_addr structure, to a character string in standard dot-decimal notation (e.g., "192.168.1.1").

The returned string is stored in a static buffer. This means that if you call inet_ntoa multiple times without saving the result, subsequent calls will overwrite the buffer from previous calls. For thread-safe operations, consider using InetNtop.

Requirements

See Also

• in_addr
• InetNtop
• InetPton

Example

#include <winsock2.h>
#include <ws2tcpip.h>
#include <stdio.h>

#pragma comment(lib, "ws2_32.lib")

int main() {
    WSADATA wsaData;
    struct in_addr addr;
    char* ip_string;

    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0) {
        fprintf(stderr, "WSAStartup failed.\n");
        return 1;
    }

    // Example IP address (localhost)
    addr.s_addr = inet_addr("127.0.0.1");

    // Convert the address to a string
    ip_string = inet_ntoa(addr);

    if (ip_string != NULL) {
        printf("IP Address (dot-decimal notation): %s\n", ip_string);
    } else {
        fprintf(stderr, "inet_ntoa failed.\n");
    }

    WSACleanup();
    return 0;
}