inet_pton()和inet_ntop()函数使用实例

概述

IP格式最常见的是使用点分10进制表示，如： xx.xx.xx.xx （IPV4地址）。
IP地址分为两类：IPv4地址和IPv6地址。

• IPv4 地址用32位来表示；
• IPv6 地址用128位来表示；

由于二进制数太长，人们为了便于记忆和识别，就把每一段8位编为一组，每组之间用点号分开。然后将每个字节（八位组）转换为等值的十进制数，大小为0至255。

IP 地址分为A、B、C、D、E等 5 大类，由IP地址第一字节的几个最高位来定义和区分，简要如下表所示

inet_pton

函数原型

#include<arpa/inet.h>intinet_pton(int af,constchar*src,void*dst);

This function converts the character string src into a network address structure in the af address family, then copies the network address structure to dst. The af argument must be either AF_INET or AF_INET6.

返回值

inet_pton() returns 1 on success (network address was successfully converted). 0 is returned if src does not contain a character string representing a valid network address in the specified address family. If af does not contain a valid address family, -1 is returned and errno is set to EAFNOSUPPORT.

inet_ntop

函数原型

#include<arpa/inet.h>constchar*inet_ntop(int af,constvoid*src,char*dst, socklen_t size);

This function converts the network address structure src in the af address family into a character string. The resulting string is copied to the buffer pointed to by dst, which must be a non-NULL pointer. The caller specifies the number of bytes available in this buffer in the argument size.

返回值

On success, inet_ntop() returns a non-NULL pointer to dst. NULL is returned if there was an error, with errno set to indicate the error.

实例

#include<arpa/inet.h>#include<stdio.h>voidTestIpv6(){char ipv6_addr[64];//内嵌 IPv4 地址的 IPv6 地址inet_pton(AF_INET6,"0:0:0:0:0:0:192.168.200.65", ipv6_addr);char ipv6_str[64]={'\0'};inet_ntop(AF_INET6, ipv6_addr, ipv6_str,64);printf("%s\n", ipv6_str);}voidTestIpv4(){int ipv4_addr;inet_pton(AF_INET,"192.168.200.65",&ipv4_addr);printf("%d\n", ipv4_addr);char ipv4_str[64]={'\0'};inet_ntop(AF_INET,&ipv4_addr, ipv4_str,64);printf("%s\n", ipv4_str);}intmain(){TestIpv6();TestIpv4();return0;}

上面代码输出结果为：

::192.168.200.65
1103669440
192.168.200.65

如果将地址设置为全 0，

inet_pton(AF_INET6,"0:0:0:0:0:0:0.0.0.0", ipv6_addr);

则打印结果为：

::

参考

inet_pton()和inet_ntop()函数详解
IPv6地址格式简介以及常见的IP地址