How to input a comma separated string in C++?

Given an input string which is comma-separated instead of space, the task is to parse this input string in C++.
First, let us understand what difference does it create if the input string is comma-separated. 
Taking input a whitespace-separated string
Taking input a whitespace-separated string in C++ is very easy. The program to do so is:

C++

#include <bits/stdc++.h>
using namespace std;

int main()
{
    string str;

    // Get the string
    getline(cin, str);

    // Print the words
    cout << str;
}

Input:

1 2 3 4 5 6

Output:

1
2
3
4
5
6

Why can’t we use the above code for comma-separated input string?
The above code works fine for a whitespace-separated input string, but for a comma-separated input string, it won’t work as expected, because the program will take complete input as a single word in the string.

Input:

1, 2, 3, 4, 5, 6

Output:

1, 2, 3, 4, 5, 6

How to input a comma separated string?
Now inorder to input a comma separated string, following approach can be used: 

1. Get the string to be taken as input in stringstream
2. Take each character of the string one by one from the stream
3. Check if this character is a comma (‘, ‘).
4. If yes, then ignore that character.
5. Else, Insert this character in the vector which stores the words

Below is the implementation of the above approach:

CPP

// C++ program to input
// a comma separated string

#include <bits/stdc++.h>
using namespace std;

int main()
{
    // Get the string
    string str = "11,21,31,41,51,61";

    vector<int> v;

    // Get the string to be taken
    // as input in stringstream
    stringstream ss(str);

    // Parse the string
    for (int i; ss >> i;) {
        v.push_back(i);
        if (ss.peek() == ',')
            ss.ignore();
    }

    // Print the words
    for (size_t i = 0; i < v.size(); i++)
        cout << v[i] << endl;
}

Output:

11
21
31
41
51
61

Time complexity: O(N).

Auxiliary Space: O(N).