How to split a string into two integers over several lines C++

Question

I've been trying to retrieve saved data from a text file. The data stored are both numbers, separated by a ~. I've managed to get it to print out one of the lines (the top line) however I've been unable to figure out how to proceed through the entire file.

There are only two numbers (integers) on each line, an X and Y position of another vector. The idea is to assign each integer to the respective variable in the vectors. I've not managed to get that far since I can't get it to go past line 1. But I'd thought that by having an array size of 2, and the array temporarily stores the value, assigns it to the vector, then overwrites it with the next value(s) that could work. But again not managed to get that far.

Below is the code I've been trying to use;

........
string loadZombieData;
loadFile >> loadZombieData; //Data gets read from the file and placed in the string

vector<string>   result; //Stores result of each split value as a string


stringstream  data(loadZombieData);
string line;
while(getline(data,line,'~'))
{
    result.push_back(line); 
}

for(int i = 0; i < result.size(); i++){
    cout << result[i] << "  ";
}
.......

Just to clarify, this is not my code, this is some code I found on Stackoverflow, so I'm not entirely certain how it all works yet. As I said, I've been trying to get it to read multiple lines, then using the for loop was going to assign the results to the other vector variables as needed. Any help is appreciated :)

Answer 1

Use two while loops:

std::vector<std::string> result;
std::vector<int> numbers;

std::string filename;
std::ifstream ifile(filename.c_str());

if (!ifile.is_open()) {
    std::cerr << "Input file not opened! Something went wrong!" << std::endl;
    exit(0);
}

std::string temp;

//loop over the file using newlines as your delimiter
while (std::getline(ifile, temp, '\n')) {
   //now temp has the information of each line.
   //create a stringstream initialized with this information:

   std::istringstream iss(temp);//this contains the information of ONE line

   //now loop over the string stream object as you would have in your code sample:
   while(getline(iss, temp,'~'))
   {
       //at this point temp is the value of a token, but it is a string
       result.push_back(temp); //note: this only stores the TOKENS as strings

       //so to store the token as a int or float, you need to convert it to that
       //via another stringstream:

       std::istringstream ss(temp);

       //if your number type is float, change it here as well as in the vector
       //initialization of `numbers`:
       int num = 0;
       //this checks the stream to ensure that conversion occurred.
       //if it did, store the number, otherwise, handle the error (quit - but, this is up to you)
       //if stringstreams aren't your cup of tea, try some others (refer to this link):
       //http://stackoverflow.com/questions/21807658/check-if-the-input-is-a-number-or-string-c/21807705#21807705
       if (!(ss >> num).fail()) {
           numbers.push_back(num);
       }
       else {
           std::cerr << "There was a problem converting the string to an integer!" << std::endl;
       }
    }
}

Note: this version stores the numbers verbatim: i.e. without a sense of how many numbers were on a line. However, that is reconcilable as all you have to do is output n numbers per line. In your case, you know every 2 numbers will be represent the numbers in a line.

This requires:

#include <string>
#include <vector>
#include <cstdlib>
#include <sstream>