Extract IP from text file C++ - c++11

Question

Im a new programmer in C++ and I want to creat a code that extract IP from text files
I tried to convert txt file to Vector(string) to be easy filtering but i cant get all formes like XXX.XXX.XXX.XXX

Answer 1

Given that the ip could be embedded in some text, we'll parse the string and fetch it.
#include <iostream>
#include <string>
#include <iterator>
#include <vector>
#include <sstream>
using namespace std;
string ip(string str)
{
//middle portion
auto firstDot = str.find_first_of('.');
auto lastDot = str.find_last_of('.');
int dotCount = 0;
for(auto i = firstDot; i <= lastDot; i++)
{
if(!isdigit(str.at(i)) && str.at(i) != '.') //e.g 127.ss.0y.1
return string("");
if(str.at(i) == '.')
dotCount++;
}
if(dotCount != 3) //eg. 127.0.1 (not sure if this is wrong though)
return string("");
string result = str.substr(firstDot,lastDot-firstDot + 1);
//left portion
size_t x = 0; //number consegative digits from the first dot
for(auto i = firstDot-1; i >= 0; i--)
{
if(!isdigit(str.at(i)))
break;
else if(x == 3) //take first 3
break;
x++;
}
if(x == 0)
return string("");
result.insert(0,str.substr(firstDot-x,x));
//right portion
size_t y = 0;
for(auto i = lastDot + 1; i < str.length(); i++)
{
if(isdigit(str.at(i)))
{
if(y == 3)
break;
result.push_back(str.at(i));
y++;
}
else
break;
}
if(y == 0)
result.push_back('0');
return result;
}
int main()
{
string test = "1111127.0.0.11111 xx23.45.12.# xxxx.34.0.13 124.sd.2.1 sd.45.56.1";
string x,y;
vector<string> ips;
stringstream stream;
stream<<test;
while(stream>>x)
if(!(y = ip(x)).empty())
ips.push_back(y);
for(auto z : ips)
cout<<z<<"\t";
cout<<endl;
system("pause");
return 0;
}

Answer 2

#include<iostream>
#include<fstream>
using namespace std;
int main() {
ifstream myReadFile;
myReadFile.open("text.txt");
char output[100];
if (myReadFile.is_open()) {
while (!myReadFile.eof()) {
myReadFile >> output;
cout<<output;
}
}
myReadFile.close();
return 0;
}
Use this if the text file only includes IP's on each line.
Or depending on what c++ you're using:
std::ifstream file("Read.txt");
std::string str;
std::string file_contents;
while (std::getline(file, str))
{
file_contents += str;
file_contents.push_back('\n');
}

Answer 3

I'm new to C++11. I did the following simple example for you. It's based on the regex library. Hope it works for you!
#include <iostream>
#include <string>
#include <regex>
int main ()
{
std::string s ("There's no place like 127.0.0.1\n");
std::smatch m;
std::regex e ("\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}");
while (std::regex_search (s,m,e)) {
for (auto x:m) std::cout << x << " ";
std::cout << std::endl;
s = m.suffix().str();
}
return 0;
}