题解 | #识别有效的IP地址和掩码 ---不想写正则的可以来拿#

#include <stdio.h>
#include <iostream>
#include <string.h>
#include <regex>
#include <algorithm>
#include <vector>
#include <stack>
#include <bitset>
using namespace std;

/*检查子网掩码*/
int checkNM(regex nex,string ips,vector<int>& total,string& NetMask,string& IP)
{
    smatch sm,nm; int count = 0; regex reg("~(.*)");
    regex_search(ips,sm,reg); int num = 0; string bits = "";
    string netmask = sm.str(1); netmask += "@";
    /*将子网掩码转化为二进制字符串*/
    for (char ch : netmask)
        {
            if(isdigit(ch))
            {
                num = num *10 + ch -'0';
            }else{
                bitset<8> bitset1(num);
                string bbits = bitset1.to_string();
                bits.append(bbits);
                num = 0;
            }
        }
    regex_match(bits,nm,nex);
    if (nm.size())
    {
        NetMask = nm.str();
        count += 1;
    }else{
        ++total[5];
    }
    return count;
}
/*检查IP*/
int checkIP(regex rex,string ips,vector<int>& total,string& NetMask,string& IP)
{    
    smatch sm; int count = 0;
        regex_search(ips, sm, rex);
        if (sm.size())
        {
            IP = sm.str();
            count += 1;
        }
    return count;
}

/*注意注意注意注意！！*/
/*建议直接拿走正则用吧，我写的太复杂了*/

int main(void)
{
    /*初始化变量*/
    string ips;//= "1.0.0.1~255.0.0.0"; 
    smatch sm,nm; 
    static string NetMask = "";
    static string IP = "";
    vector<int> total(7,0);
    //string APattern = "((1[0-2][0-6])|([1-9][0-9])|([1-9]))\\.(([1-2][0-9][0-9]|[1-9][0-9]|[0-9])\\.){2}([1-2][0-9][0-9]|[1-9][0-9]|[0-9])~255\\.0\\.0\\.0";
    /*正则*/
    string APattern = "(^1[0-1][0-9]|^[1-9][0-9]|^[1-9]|^12[0-6])\\.((1[0-9][0-9]|2[0-4][0-9]|25[0-4]|[1-9][0-9]|[0-9])\\.){2}(1[0-9][0-9]|2[0-4][0-9]|25[0-4]|[1-9][0-9]|[0-9])";
    string BPattern = "(^12[8-9]|^1[3-8][0-9]|^19[0-1])\\.((1[0-9][0-9]|2[0-4][0-9]|25[0-4]|[1-9][0-9]|[0-9])\\.){2}(1[0-9][0-9]|2[0-4][0-9]|25[0-4]|[1-9][0-9]|[0-9])";
    string CPattern = "(^19[2-9]|^2[0-1][0-9]|^22[0-3])\\.((1[0-9][0-9]|2[0-4][0-9]|25[0-4]|[1-9][0-9]|[0-9])\\.){2}(1[0-9][0-9]|2[0-4][0-9]|25[0-4]|[1-9][0-9]|[0-9])";
    string DPattern = "(^22[4-9]|^23[0-9])\\.((1[0-9][0-9]|2[0-4][0-9]|25[0-4]|[1-9][0-9]|[0-9])\\.){2}(1[0-9][0-9]|2[0-4][0-9]|25[0-4]|[1-9][0-9]|[0-9])";
    string EPattern = "^24[0-9]|^25[0-5]\\.((1[0-9][0-9]|2[0-4][0-9]|25[0-4]|[1-9][0-9]|[0-9])\\.){2}(1[0-9][0-9]|2[0-4][0-9]|25[0-4]|[1-9][0-9]|[0-9])";
    string NPattern = "1+0+$";
    string FPattern = "(^0|^127).*";
    regex Aregex(APattern);regex Bregex(BPattern);regex Cregex(CPattern);
    regex Dregex(DPattern);regex Nregex(NPattern);regex Eregex(EPattern);
    regex Fregex(FPattern);

    while ( cin >> ips )
    {
       regex_match(ips,sm,Fregex);
       if (sm.size())
       {
           continue;
       }
       if (!checkNM(Nregex,ips,total,NetMask,IP))
       {
           continue;
       }
       if (checkIP(Aregex, ips,total,NetMask,IP))
       {
            ++total[0];
            IP.substr(0,2) == "10" && IP.substr(2,1) == "." ? ++total[6] : total[6]; 
            continue;
       }
       if (checkIP(Bregex, ips,total,NetMask,IP))
       {
               ++total[1];
           if (IP.substr(0,3) == "172")
           {
               int num = 0;
               for (int i = 4 ;i <=6 ;++i )
               {
                   num = num * 10 + IP[i]-'0';
               }
               if (num >= 16 && num <= 31)
               {
                   ++total[6];
               }
           } 
         continue;
       }
       if (checkIP(Cregex, ips,total,NetMask,IP))
       {
            ++total[2];
            IP.substr(0,3) == "192" && IP.substr(4,3) == "168" ? ++total[6] : total[6];
            continue;
       }
       if (checkIP(Dregex, ips,total,NetMask,IP) && NetMask != "")
       {
           ++total[3];
           continue;
       }
       if (checkIP(Eregex, ips , total,NetMask,IP) && NetMask != "")
       {
           ++total[4];
           continue;
       }
        ++total[5];
    }
    
    for (int i = 0;i <7;++i)
    {
        printf("%d ",total[i]);
    }
}