C++如何获取本机的IP地址

C++如何获取本机IP地址，可以通过以下步骤实现：

1. 加载网络库

为了使用网络相关的库函数，需要在程序中加载网络库。可以在程序中包含Winsock2.h头文件，并添加相应的库路径和库文件，如下所示：

#include <Winsock2.h>
#pragma comment(lib, "ws2_32.lib")

1. 初始化Winsock

在使用Winsock之前，需要初始化它。可以调用WSAStartup函数进行初始化，如下所示：

WSADATA wsaData;
int result = WSAStartup(MAKEWORD(2, 2), &wsaData);
if (result != 0) {
    printf("WSAStartup failed: %d\n", result);
    return 1;
}

1. 调用gethostname获取主机名

主机名是本机的唯一标识符，可以通过调用gethostname函数来获取它，如下所示：

char hostname[256];
if (gethostname(hostname, sizeof(hostname)) == SOCKET_ERROR) {
    printf("Failed to get hostname: %d\n", WSAGetLastError());
    WSACleanup();
    return 1;
}

1. 调用gethostbyname获取IP地址

获取主机名后，可以通过调用gethostbyname函数来获取IP地址，如下所示：

struct hostent* host;
host = gethostbyname(hostname);
if (host == NULL) {
    printf("Failed to get IP address: %d\n", WSAGetLastError());
    WSACleanup();
    return 1;
}
char* ip = inet_ntoa(*(struct in_addr*)*host->h_addr_list);
printf("IP address: %s\n", ip);

完整示例代码如下所示：

#include <stdio.h>
#include <Winsock2.h>
#pragma comment(lib, "ws2_32.lib")

int main() {
    WSAData wsaData;
    int result = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (result != 0) {
        printf("WSAStartup failed: %d\n", result);
        return 1;
    }

    char hostname[256];
    if (gethostname(hostname, sizeof(hostname)) == SOCKET_ERROR) {
        printf("Failed to get hostname: %d\n", WSAGetLastError());
        WSACleanup();
        return 1;
    }

    struct hostent* host;
    host = gethostbyname(hostname);
    if (host == NULL) {
        printf("Failed to get IP address: %d\n", WSAGetLastError());
        WSACleanup();
        return 1;
    }

    char* ip = inet_ntoa(*(struct in_addr*)*host->h_addr_list);
    printf("IP address: %s\n", ip);

    WSACleanup();
    return 0;
}

示例1：

假设本机主机名为"MyComputer"，运行程序后可以得到输出结果：

IP address: 192.168.0.123

示例2：

将主机名定义为字符串常量，程序如下所示：

#include <stdio.h>
#include <Winsock2.h>
#pragma comment(lib, "ws2_32.lib")

int main() {
    WSAData wsaData;
    int result = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (result != 0) {
        printf("WSAStartup failed: %d\n", result);
        return 1;
    }

    const char* hostname = "MyComputer";
    struct hostent* host;
    host = gethostbyname(hostname);
    if (host == NULL) {
        printf("Failed to get IP address: %d\n", WSAGetLastError());
        WSACleanup();
        return 1;
    }

    char* ip = inet_ntoa(*(struct in_addr*)*host->h_addr_list);
    printf("IP address: %s\n", ip);

    WSACleanup();
    return 0;
}

运行程序后可以得到输出结果：

IP address: 192.168.0.123