C++ Vector to CSV by adding Comma after each element

Question

vector v;
v.push_back(\"A\");
v.push_back(\"B\");
v.push_back(\"C\");
v.push_back(\"D\");

for (vector::iterator it = v.begin(); it!=v.end()         


        

Answer 1

Loop way:

for (vector<string>::iterator it = v.begin(); it != v.end(); ++it) {
   if (it != v.begin()) cout << ',';
   cout << *it;
}

"Clever" way:

#include <algorithm>
#include <iterator>

if (v.size() >= 2)
   copy(v.begin(), v.end()-1, ostream_iterator<string>(cout, ","));
if (v.size() >= 1)
   cout << v.back();

Answer 2

To avoid the trailing comma, loop until v.end() - 1, and output v.back() for instance:

#include <vector>
#include <iostream>
#include <iterator>
#include <string>
#include <iostream>

template <class Val>
void Out(const std::vector<Val>& v)
{
    if (v.size() > 1)
        std::copy(v.begin(), v.end() - 1, std::ostream_iterator<Val>(std::cout, ", ")); 
    if (v.size())
        std::cout << v.back() << std::endl;
}
int main()
{
    const char* strings[] = {"A", "B", "C", "D"};
    Out(std::vector<std::string>(strings, strings + sizeof(strings) / sizeof(const char*)));

    const int ints[] = {1, 2, 3, 4};
    Out(std::vector<int>(ints, ints + sizeof(ints) / sizeof(int)));
}

BTW you posted:

vector<string> v; 
//...
for (vector<int>::iterator it = v.begin(); //...

which is unlikely to compile :)

Answer 3

You could output the commas in your for loop:

for (vector<int>::iterator it = v.begin(); it!=v.end(); ++it) {
//printout 
   cout << *it << ", " << endl;
}

Or, you could use the copy algorithm.

std::copy(v.begin(), v.end(), std::ostream_iterator<char*>(std::cout, ", "));

Answer 4

With a normal ostream_iterator, you'll get a comma after every data item -- including the last, where you don't want one.

I posted an infix_iterator in a previous answer that fixes this problem, only putting commas between the data items, not after the final one.

Answer 5

Below should do the job. Thanks.

    ofstream CSVToFile("ava.csv", ios::out | ios::binary);
    //////////////////vector element to CSV////////////////////////////////////////
for (std::vector<string>::iterator i = ParamHeaders.begin(); i != ParamHeaders.end(); i++)
{
    if (i != ParamHeaders.begin()) 
    {
            CSVToFile << ",";
            std::cout << ",";
    }
    std::cout << *i;
    CSVToFile << *i;

}