计算子网包含多少ip（windows网络编程学习笔记）

一、计算子网原理
1.将IP地址与子网掩码按位与，即可计算出子网地址：
  <子网地址> = & <子网掩码>

2.将子网掩码按位非，然后在ip地址按位或运算得出广播地址：
  <广播地址> = | (~<子网掩码>)

二、具体实现：

#include
#include
#include
#pragma comment(lib,"ws2_32.lib")
using namespace std;

//正则表达式校验ip合法性
bool isValidIP(const char *ip){
	   if(ip == NULL)
		      return false;
	   regex pattern("^(?!^255(\.255){3}$)(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9])(\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)){2}\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[0-9])$");

   	return regex_match(ip,pattern);
}

//校验子网掩码的合法性
bool isValidMask(const char *mask){
	    if(mask == NULL)	
	       	return false;
	    regex pattern("^((128|192)|2(24|4[08]|5[245]))(\.(0|(128|192)|2((24)|(4[08])|(5[245])))){3}$");
	    
	    return regex_match(mask,pattern);
}
bool  calculateSubnet(const char *ip,const char *mask){
    	if(ip == NULL || mask == NULL){
		      return false;
	    }
	    printf("ip = %s\n",ip);
    if(!isValidIP(ip)){
	       	printf("invalid ip\n");
       		getchar();
	       	exit(0);
	    }
	    printf("mask = %s\n",mask);
	    if(!isValidMask(mask)){
	        	printf("invalid mask\n");
		        getchar();
	        	exit(0);
    	}
	    unsigned long netaddr = ntohl(inet_addr(ip));
	    unsigned long netmask = ntohl(inet_addr(mask));
    	unsigned long first_netaddr = netaddr & netmask;
    	unsigned long broadcast = netaddr | (~netmask);
	    long num = broadcast - first_netaddr - 1;
	    printf("Number of valid ips: %d\n",num);
    	for(unsigned long i = first_netaddr + 1; i < broadcast ; i++){

	    	    sockaddr_in addr;
	    	    addr.sin_addr.S_un.S_addr = ntohl(i);
	        	printf("%s\n",inet_ntoa(addr.sin_addr));
     }
     	return true;
}
int main(){
     	const char *ip = "192.168.0.55";
	     const char *mask = "255.255.255.0";
	     //char ip[32] = {0};
     	//char mask[32] = {0};
     	//scanf("%s %s",ip,mask);
     	calculateSubnet(ip,mask);
	     getchar();
     	return 0;
}