如何进行字符串处理? [英] How can I conduct the character strings?

问题描述

大家好.
我有一个关于字符串的问题.即:

我编写了一个应用程序来获取我的本地IP地址，例如192.168.0.35.但我想将其设为192.168.0.34.如何制作?
就是说，我要在获得的IP地址中减去我的最后一个数字.

//获得IP的应用程序代码:

Hello, everyone.
I have a question about character string. that is:

I write an application to get my local IP Address,such 192.168.0.35 . But I want to make it being 192.168.0.34.How can I make it ?
That is to say, I want to make my the last number minus one in the IP Address that I get.

//The application code getting IP:

#include"windows.h"
#include<stdlib.h>
#include<conio.h>
#pragma comment(lib,"ws2_32.lib")
void CheckIP(void) //define this function to get the local IP
{
    WSADATA wsaData;
    char name[255];
    char *ip;
    PHOSTENT hostinfo;

    //MAKEWORD（） to get the Winsock version
    if ( WSAStartup( MAKEWORD(2,0), &wsaData ) == 0 )
    {
        if( gethostname ( name, sizeof(name)) == 0)
        {
            if((hostinfo = gethostbyname(name)) != NULL)
            {
                ip = inet_ntoa (*(struct in_addr *)*hostinfo->h_addr_list);
                printf("\n\n    Your IP is ：%s\n\n",ip); //Output the IP Address
            }
        }
        WSACleanup( );     //unload Winsock library
} }

int main(void)
{
    CheckIP();

    getch();
    return 0;
}

例如:

我得到的本地IP .......我想要的字符串
192.168.0.35 ............. 192.168.0.34
192.168.5.62 ............. 192.168.5.61
192.168.12.09 ............. 192.168.12.08

有人可以帮我弄弦吗?请告诉我您的代码.
预先谢谢您.

for example:

the local IP I get ....... the string that I want
192.168.0.35 ............. 192.168.0.34
192.168.5.62 ............. 192.168.5.61
192.168.12.09 ............. 192.168.12.08

Could someone help me get the strings ? Please show me your code.
Thank you in advance.

推荐答案

如果它是字符串，例如

if it is a string, for instance

char sip[]= "192.168.0.35";

然后您可以做(错误处理留给读者...):

Then you may do (error handling left to the reader...):

int a,b,c,d;
char sip[] = "192.168.0.35";
char snewip[sizeof(sip)];
sscanf(sip,"%d.%d.%d.%d",&a,&b,&c,&d);
if (d>0)  d--;
sprintf(snewip,"%d.%d.%d.%d",a,b,c,d);

为什么不从主机地址表中的相关字节值中减去1?请参见此处 [

Why not just subtract 1 from the relevant byte value in your host address table? See here[^] for details of the various returned structures.

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