Parsing a string of integers into multiple integers

[socaldavec]

I have a string "n,n,n" where each n is a value 0 to 19.

I know I can use find(), substr(), and atoi() to breakout the integers, but I saw somewhere someone using istringstream (I think) with code something like " buffer >> int1 >> int2 >> int3 ". Does this make sense to anyone? Any help or pointers would be appreciated.

I saw the answer to this somewhere, but I've search extensively and I can't find it. I could look through browser history for a couple hours, but was hoping somebody knows this one.

~dave

 
void breakOut(string str, int &i, int &j, int &k){
  //declare local variables
  istringstream buffer(str);
  buffer >> i >> j >> k;
}
 
...

 //Initialize cave;
    // after great frustration trying to randomize the cave, I'm hard coding it.
  saRoom[0] = "1,10,19"; saRoom[1] = "0,2,6"; saRoom[2] = "1,3,13"; saRoom[3] = "2,4,8";
  saRoom[4] = "3,5,15"; saRoom[5] = "4,6,12"; saRoom[6] = "1,5,7"; saRoom[7] = "6,8,18";
  saRoom[8] = "3,7,9"; saRoom[9] = "8,10,17"; saRoom[10] = "0,9,11"; saRoom[11] = "10,12,14";
  saRoom[12] = "5,11,13"; saRoom[13] = "2,12,14"; saRoom[14] = "11,13,15"; saRoom[15] = "4,14,16";
  saRoom[16] = "15,17,19"; saRoom[17] = "9,16,18"; saRoom[18] = "7,17,19"; saRoom[19] = "0,16,18";

  //Place objects (continued)
  breakOut(saRoom[iERm], iC1, iC2, iC3);
  cout << "iErm = " << iERm <<".  iC1 = " << iC1 << ".  iC2 = " << iC2 << ". iC3 = " << iC3 << ".\n";
}

Output :
iErm =7. iC1 = 6. iC2 = 0. iC3 = 0.

[Bourgond Aries]

You could use C++11's std::to_string

or:

std::stringstream ss;
        ss << 32; // The integer
        std::string str;
        ss >> str;

[socaldavec]

You could use C++11's std::to_string

or

std::stringstream ss;
        ss << 32; // The integer
        std::string str;
        ss >> str;

@Bourgond Aries - I'm not sure how your answer fits my question.

@Everyone - I ended up doing it the hard way:

void breakOut(string str, int &i, int &j, int &k){
  //declare local variables
  int lc1, lc2;
  string sTemp;
  size_t zPos;

  zPos = str.find(',');
  lc1 = static_cast<int>(zPos);
  zPos = str.find(',', zPos+1);
  lc2 = static_cast<int>(zPos);
  sTemp = str.substr(0,lc1);
  i = atoi(sTemp.c_str());
  sTemp = str.substr(lc1+1,(lc2-lc1-1));
  j = atoi(sTemp.c_str());
  sTemp = str.substr(lc2+1);
  k = = atoi(sTemp.c_str());
}

I'd still like to know the elegant solution that allows me to use something like

buffer >> i >> j >> k;

[Bourgond Aries]

Oh, sorry, I think I misunderstood.

istringstream and stringstream's operator >> separate by whitespaces.

You could simply use std::replace_if and replace all occurences of ',' in your string, and then feed it into your original breakOut function.

[Chervil]

Yes, replace comma with space:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

#include <iostream> #include <iomanip> #include <string> #include <sstream> using namespace std; void breakOut(string str, int &i, int &j, int &k); int main() { std::string saRoom[20] = { "1,10,19", "0,2,6", "1,3,13", "2,4,8", "3,5,15", "4,6,12", "1,5,7", "6,8,18", "3,7,9", "8,10,17", "0,9,11", "10,12,14", "5,11,13", "2,12,14", "11,13,15", "4,14,16", "15,17,19", "9,16,18", "7,17,19", "0,16,18" }; int a, b, c; for (int i=0; i<20; i++) { breakOut(saRoom[i], a, b, c); cout << setw(10) << saRoom[i] << setw(4) << a << setw(4) << b << setw(4) << c << endl; } return 0; } void breakOut(string str, int &i, int &j, int &k) { // replace all commas with spaces size_t pos = 0; while ((pos = str.find(',',pos)) != string::npos) str[pos] = ' '; istringstream buffer(str); buffer >> i >> j >> k; }

1,10,19 1 10 19 0,2,6 0 2 6 1,3,13 1 3 13 2,4,8 2 4 8 3,5,15 3 5 15 4,6,12 4 6 12 1,5,7 1 5 7 6,8,18 6 8 18 3,7,9 3 7 9 8,10,17 8 10 17 0,9,11 0 9 11 10,12,14 10 12 14 5,11,13 5 11 13 2,12,14 2 12 14 11,13,15 11 13 15 4,14,16 4 14 16 15,17,19 15 17 19 9,16,18 9 16 18 7,17,19 7 17 19 0,16,18 0 16 18

[Duthomhas]

If you don't mind a slightly longer compile time you can get much faster results using Boost Spirit.

#include <iomanip>
#include <iostream>
#include <string>
#include <vector>

#include <boost/spirit/include/qi.hpp>

void breakOut(const std::string& str, int &i, int &j, int &k);

int main()
{
    using namespace std;
    string saRoom[20] = {
        "1,10,19",  "0,2,6",    "1,3,13",   "2,4,8",
        "3,5,15",   "4,6,12",   "1,5,7",    "6,8,18",
        "3,7,9",    "8,10,17",  "0,9,11",   "10,12,14",
        "5,11,13",  "2,12,14",  "11,13,15", "4,14,16",
        "15,17,19", "9,16,18",  "7,17,19",  "0,16,18"
    };

    int a, b, c;

    for (int i=0; i<20; i++)
    {
        breakOut(saRoom[i], a,  b, c);
        cout << setw(10) << saRoom[i]
             << setw(4) << a << setw(4) << b << setw(4) << c << endl;
    }

    return 0;
}

void breakOut(const std::string& str, int &i, int &j, int& k)
{
    using namespace boost::spirit::qi;
    std::vector <int> results;
    phrase_parse( str.begin(), str.end(), (int_ % ','), space, results );
    i = results[ 0 ];
    j = results[ 1 ];
    k = results[ 2 ];
}

Hope this helps.