ipv4 字符串 unsigned int 轉換

#include <iostream>
#include <string>
using namespace  std;

unsigned int    convert_ip_2_uint(string& strip)
{
	const char* pstr = strip.c_str();

	int tmparr[4] = {0};
	int nBegin =0;
	int nPoint = 0;
	
	for(int i=0;i<(int)strip.length();i++)
	{
		if(pstr[i] == '.' || i == (int)strip.length()-1)
		{
			string strtmp = strip.substr(nBegin,i);
			tmparr[nPoint] = atoi(strtmp.c_str());
			if(tmparr[nPoint] > 255)
			{
				return 0;
			}
			nPoint ++;
			if(nPoint >= 4)
			{
				break;
			}
			nBegin = i+1;
		}
	}

	if(nPoint != 4)
	{
		return 0;
	}

	unsigned int nip = 0;
	char* pip = (char*)&nip;
	*pip++ = (char)tmparr[3];
	*pip++ = (char)tmparr[2];
	*pip++ = (char)tmparr[1];
	*pip = (char)tmparr[0];

	return nip;
}

string convert_uint_2_ip(unsigned int nip)
{
	string ipstr;
	unsigned char* pip = (unsigned char*)&nip;

	int iparr[4] = {0};

	iparr[3] = (int)*pip++;
	iparr[2] = (int)*pip++;
	iparr[1] = (int)*pip++;
	iparr[0] = (int)*pip;

	char szip[128] = {0};
	for(int i=0;i<4;i++)
	{
		itoa(iparr[i],szip,10);

		if(i != 3)
		{
			ipstr = ipstr + szip + ".";
		}
		else
		{
			ipstr = ipstr + szip;
		}
	}

	return ipstr;
}

int main()
{
	while(true)
	{
		cout<<"IP:";
		string ipstr;
		cin>>ipstr;
		if(ipstr == "exit")
		{
			break;
		}
		else
		{
			unsigned int nip = convert_ip_2_uint(ipstr);
			if(nip != 0)
			{
				cout<<"v4=>"<<nip<<"=>"<<convert_uint_2_ip(nip).c_str()<<endl;
			}
			else
			{
				cout<<"IP格式錯誤!"<<endl;
			}			
		}
	}
	return 0;
}