concatenate numbers with multiple periods

[Johnnyboy]

I'm trying to generate a few random ip addresses to put into an array but I can't remember how to concatenate multiple numbers with multiple periods.

eg: 100.252.1.62

Please only post hints on how to approach this problem so I can solve it myself.

Thanks.

[Moschops]

Turn them into strings.

[Johnnyboy]

Is it possible to do this without using sstream?

So far I have made an int function that returns a random number from 0 to 255. How can I turn that into a string?

int randgen(int minimun, int maximum) where minimum is 0 and maximum is 255.

[wolfgang]

Without using stringstream you would need to write your own function that transcribes each integer into its corresponding char value. sstream is faster than writing a function to transform large numbers but of course it has its own problems.

You could try boost::lexical_cast, but I recommend sstream.

template <typename T> std::string to_string (T variable)
{
  std::ostringstream ss();
  ss << variable;
  return ss.str();
}

[stereoMatching]

another solution

int const NUM = 1000;
//the length is 12 because of the the maximum number of int + sign + '\0'
//this could be different at different platforms or compiler
char intToStr[12]; 
sprintf(intToStr, "%i", NUM);
cout<<"intToStr = "<<intToStr<<"\n";

this way is faster but less flexible and unsafe
choose the solutions you need according to your application

[Johnnyboy]

Many thanks for the replies!

I don't know if I should make a new thread or not but I made my program with stringstream and now I have a string array of 30 IPv4 addresses.

My question is: How can I sort my string array of numeric IP addresses in ascending order? I only know bubble sort to sort integer arrays and I haven't learned how to use <algorithm> yet.

[stereoMatching]

std::vector<std::string> sortString;
  sortString.push_back("201");
  sortString.push_back("222");
  sortString.push_back("333");
  sortString.push_back("532");
  
//descending
  std::sort(sortString.begin(), sortString.end(), std::greater<std::string>());
  std::copy(sortString.begin(), sortString.end(), std::ostream_iterator<std::string>(cout, "\n"));

//ascending
 std::sort(sortString.begin(), sortString.end());
  std::copy(sortString.begin(), sortString.end(), std::ostream_iterator<std::string>(cout, "\n"));

you could implement the algorithm by yourself, this could be a good practice
besides bubble sort, there are selection sort, quick sort, heap sort, merge sort and other's

[moorecm]

Note that the sorting above will be lexicographical not numerical.

[stereoMatching]

you are right
it should be convert to size_t first if it have to base on numerical
Thanks for your correction

  std::vector<size_t> sortNum;
  sortNum.push_back(2);
  sortNum.push_back(9);
  sortNum.push_back(333);
  sortNum.push_back(532);

  std::sort(sortNum.begin(), sortNum.end());    
  std::copy(sortNum.begin(), sortNum.end() - 1, std::ostream_iterator<size_t>(cout, "."));  
  cout<<sortNum.back()<<"\n";
  

According to the idea of Duous, this should be better

[Duthomhas]

Since you only need the strings when you want a human to look at them, why not store them as numbers internally, then convert them on output?

[ne555]

If you want to sort the IP, you will need to provide a function that compares two IP.

struct ip{
  unsigned char code[4];
};

bool comp(const ip &a, const ip &b){
//compare element by element
  int K;
  for(K=0; K<4 && a.code[K]==b.code[K]; K++)
    ;
  if( K==4 ) return false; //equal
  return a.code[K] < b.code[K];
}

You could change the representation to a single number and compare that.

Edit: simpler
typedef std::vector<unsigned char> ip_code;

[Johnnyboy]

I can't figure it out.

I print out the first and last 3 items of my array after sorting and it only sorts up to 99. I know there are strings that begin with 255... but it doesn't seem know those are larger than 99.

0.100.79.127
0.102.68.143
0.103.77.203
99.93.122.155
99.93.2.173
99.95.119.108

[stereoMatching]

please show us your code
if you just apply std::sort on std::string
it would sorted by lexicographical not numerical

[Duthomhas]

...which is why I recommend only converting to string on output...

[wolfgang]

Why are you not storing them as shorts and then just outputting a string?

If you want to accept std::string input I recommend this quick fix. It does use stringstreams.

IP:: IP (std::string str)
{
  this->_size = 4;
  std::replace(str.begin(), str.end(), '.', ' ');

  std::istringstream ss(str);
  for (size_t i = 0; i < _size; ++i)
    ss >> this->_ip[i];
}

Then _ip[] is array of 4 shorts (or 4 unsigned chars). Then on output put it back into a string.

[Johnnyboy]

Okay, I am really struggling with this, here is my source code, but when I sort it thinks 0 is the lowest and 9 is highest, but 255 should be higher than 99. I have been trying really hard to use everyone's suggestions, but I am stumped: my C++ knowledge is very limited.

I want to try it your way, Duoas, but I can't figure out how to concatenate 4 random shorts without turning them into strings first.

EDIT: I just realized that I can make 4 arrays then concatenate them after I've sorted them and add periods!! I feel like an idiot. I was thinking too much into this. I truly appreciate all your help.

[Duthomhas]

...er, that still won't sort properly...

struct IPv6_Address
  {
  char octets[ 8 ];
  ...
  };

template <typename Char, typename Traits>
std::basic_ostream <Char, Traits> &
operator << (
  std::basic_ostream <Char, Traits> & outs,
  const IPv6_Address& ipaddress
  ) {
  outs << ipaddress.octets[ 0 ];
  size_t N = (std::count( ipaddress.octets + 4, ipaddress.octets + 8, 0 ) == 4) ? 4 : 8;
  for (unsigned n = 1; n < N; n++)
    outs << "." << ipaddress.octets[ n ];
  return outs;
  }

[Johnnyboy]

what is a struct? is that a data type like void or main?

I wish I could understand that but I'm not at that level yet. This is what I have so far and you're correct.. my output is not what I want because there are a lot of repeats due to the way I am sorting I think?

[Albatross]

Structs are a form of "composite" data type. A struct... is basically a set of variables of differing names bundled into one type.

With structs, you can create your own types. A little template you may want to use is:

struct name
{
    //Variables.
};

Since you're creating your own type, you will need to create an instance of it, just like you would an int.

That was not the best explanation, but I hope it's enough. If it's not, then try this:
http://cplusplus.com/doc/tutorial/structures/

Happy coding! :)

-Albatross

[Johnnyboy]

Thanks