Parsing a comma-delimited std::string [duplicate]

Answer 1

Input one number at a time, and check whether the following character is ,. If so, discard it.

#include <vector>
#include <string>
#include <sstream>
#include <iostream>

int main()
{
    std::string str = "1,2,3,4,5,6";
    std::vector<int> vect;

    std::stringstream ss(str);

    for (int i; ss >> i;) {
        vect.push_back(i);    
        if (ss.peek() == ',')
            ss.ignore();
    }

    for (std::size_t i = 0; i < vect.size(); i++)
        std::cout << vect[i] << std::endl;
}

Answer 2

Alternative solution using generic algorithms and Boost.Tokenizer:

struct ToInt
{
    int operator()(string const &str) { return atoi(str.c_str()); }
};

string values = "1,2,3,4,5,9,8,7,6";

vector<int> ints;
tokenizer<> tok(values);

transform(tok.begin(), tok.end(), back_inserter(ints), ToInt());

Answer 3

Yet another, rather different, approach: use a special locale that treats commas as white space:

#include <locale>
#include <vector>

struct csv_reader: std::ctype<char> {
    csv_reader(): std::ctype<char>(get_table()) {}
    static std::ctype_base::mask const* get_table() {
        static std::vector<std::ctype_base::mask> rc(table_size, std::ctype_base::mask());

        rc[','] = std::ctype_base::space;
        rc['\n'] = std::ctype_base::space;
        rc[' '] = std::ctype_base::space;
        return &rc[0];
    }
}; 

To use this, you imbue() a stream with a locale that includes this facet. Once you've done that, you can read numbers as if the commas weren't there at all. Just for example, we'll read comma-delimited numbers from input, and write then out one-per line on standard output:

#include <algorithm>
#include <iterator>
#include <iostream>

int main() {
    std::cin.imbue(std::locale(std::locale(), new csv_reader()));
    std::copy(std::istream_iterator<int>(std::cin), 
              std::istream_iterator<int>(),
              std::ostream_iterator<int>(std::cout, "\n"));
    return 0;
}

Answer 4

string exp = "token1 token2 token3";
char delimiter = ' ';
vector<string> str;
string acc = "";
for(int i = 0; i < exp.size(); i++)
{
    if(exp[i] == delimiter)
    {
        str.push_back(acc);
        acc = "";
    }
    else
        acc += exp[i];
}

Answer 5

#include <sstream>
#include <vector>
#include <algorithm>
#include <iterator>

const char *input = ",,29870,1,abc,2,1,1,1,0";
int main()
{
    std::stringstream ss(input);
    std::vector<int> output;
    int i;
    while ( !ss.eof() )
    {
       int c =  ss.peek() ;
       if ( c < '0' || c > '9' )
       {
          ss.ignore(1);
          continue;
        }

       if (ss >> i)
       {
          output.push_back(i);
        }

    }

    std::copy(output.begin(), output.end(), std::ostream_iterator<int> (std::cout, " ") );
    return 0;
}

Answer 6

Something less verbose, std and takes anything separated by a comma.

stringstream ss( "1,1,1,1, or something else ,1,1,1,0" );
vector<string> result;

while( ss.good() )
{
    string substr;
    getline( ss, substr, ',' );
    result.push_back( substr );
}