Storing values from a vector to a string as comma seperated values

Question

how can I store the values returned from a function to a string as comma seperated values. Can anyone help me..?

const myVector &vecList = obj.get_List();
vector<myNumVector *>::const_iterator iter;
for (iter= vecList.begin(); iter!= vecList.end(); iter++)
{
  string myNum = (*iter)->get_myNum();
  string myNumList = ? 
  //myNumList should be = drt123,ret34,dfghgd234.... if these are the return values
} //can we achive this by use of some sting functions..?

have a look at the `std::string` concatenation operations (`+` and `append()`) — Nim, Apr 29 '11 at 14:13
See http://stackoverflow.com/questions/5689003/how-to-implode-a-vector-of-strings-into-a-string-the-elegant-way/5707947#5707947 — Robᵩ, Apr 29 '11 at 14:21
See http://stackoverflow.com/questions/3496982/printing-lists-with-commas-c/3497021#3497021 — Robᵩ, Apr 29 '11 at 14:22
@vidhya, are you more troubled by "How do I convert the return from `get_nyNum()` to an `std::string`?" or by "How do I insert commas between the strings?" — Robᵩ, Apr 29 '11 at 14:46

Robᵩ · Accepted Answer · 2011-04-29T14:55:30.050

1

As can be seen from the links I posted, there are lots of ways to do this. Here is, I believe, the simplest:

#include <vector>
using std::vector;

#include <string>
using std::string;

#include <boost/assign/list_of.hpp>
using boost::assign::list_of;
namespace ba = boost::assign;

vector<string> victor = list_of
  ("Clarence Oveur")
  ("Roger Murdock")
  ("Victor Basta");

int main() {
  string result;
  for(vector<string>::iterator it = victor.begin();
    it != victor.end();
    ++it) {
    if(it != victor.begin()) {
      result += ", ";
    }
    result += *it;
  }
  cout << result << "\n";
}

EDIT: To translate directly to OP's question:

const myVector &vecList = obj.get_List();
vector<myNumVector *>::const_iterator iter;
string myNumlist;
for (iter= vecList.begin(); iter!= vecList.end(); iter++)
{
  string myNum = (*iter)->get_myNum();
  if(iter!=vecList.begin()) {
    nyNumList += ",";
  }
  myNumList += myNum;
}

EDIT: Simplified by removing bool first from previous solution.

edited Apr 29 '11 at 14:55

answered Apr 29 '11 at 14:38

Robᵩ

163,533
20
239
308

Except that this also assumes that `*it` will return the value of the function call `it->get_MyNum()`, which is at the end of the day what I think OP is having trouble with, – John Dibling Apr 29 '11 at 14:40
@John, you should see my [strict weak ordering](http://en.wikipedia.org/wiki/Strict_weak_ordering) example from [Airplane II](http://www.uselessmoviequotes.com/umq_a004.htm). – Robᵩ Apr 29 '11 at 14:43
@John, thanks pointing out the disconnect with OP's question. Is this better? – Robᵩ Apr 29 '11 at 14:49
I think so, we'll just have to see how OP responds since the question doesn't really clarify what exactly they are having trouble with. – John Dibling Apr 29 '11 at 14:53

Marco Kinski · Answer 2 · 2021-05-16T17:36:05.713

#include <vector>
#include <algorithm>
#include <iostream>
#include <iterator>
#include <sstream>
    
int main () {
    std::vector<int> v;
    v.push_back(1);
    v.push_back(2);
    v.push_back(3);
    v.push_back(4);

    std::stringstream list;
    std::copy(v.begin(), v.end(), std::ostream_iterator<int>(list, ","));

    std::cout << list.str();

    return 0;
}

Outputs: 1,2,3,4,

more modern approach, also solving the trailing ","

#include <string>
#include <numeric>
#include <iostream>

int main() {
    const auto v = {1, 2, 3, 4};
    const auto list = std::accumulate(begin(v), end(v), std::string{}, [](const std::string& so_far, const auto& next) {
        return so_far + (so_far.empty() ? "" : ", ") + std::to_string(next);
    });

    std::cout << list;

    return 0;
}

A correct solution ought to omit the trailing comma – Codure Feb 27 '14 at 15:38 — Codure, Feb 27 '14 at 15:38

Cubbi · Answer 3 · 2011-04-29T14:40:51.403

0

Yes, this can be achieved using string functions, along with a handful other methods.

Given a string myNumList defined outside the loop, you could simply

myNumList += "," + myNum;

although that would add an extraneous comma in the beinning, so check if iter is pointing there first:

if(iter != vecList.begin())
    myNumList += ',';
myNumList += myNum;

edited Apr 29 '11 at 14:40

answered Apr 29 '11 at 14:15

Cubbi

46,567
13
103
169

2

surely this will add an extra `,` at the begining? – Nim Apr 29 '11 at 14:17
@Nim yes, of course. Got sucked into a meeting before I could correct. – Cubbi Apr 29 '11 at 14:43

Storing values from a vector to a string as comma seperated values

3 Answers3