Question

I’m reading C++ Primer and working on its exercise. It want me to get user’s input and separate by space ' '. So I come up with 2 solution.

First solution:

vector<string> vector1;
string input;
string temp = ""; // temperary hold each word value in input.

string x1 = "";
char x2 = 'b';

x1 += x2;

cout << x1 << endl;

getline(cin, input);

input += " ";

for (string::size_type index = 0; index != input.size(); index++)
{
    if (!isspace(input[index]))
    {
        temp += input[index];
    }
    else
    {
        if (temp.size() > 0)
        {
            vector1.push_back(temp);
            temp = "";
        }
    }
}

Second solution

vector<string> vector1;
string input;
string temp = ""; // temperary hold each word value in input.

string x1 = "";
char x2 = 'b';

x1 += x2;

cout << x1 << endl;

getline(cin, input);

//input += " ";

for (string::size_type index = 0; index != input.size(); index++)
{
    if (!isspace(input[index]))
    {
        temp += input[index];
    }
    else
    {
        if (temp.size() > 0)
        {
            vector1.push_back(temp);
            temp = "";
        }
    }
}

if (!temp.empty())
{
    vector1.push_back(temp);
}

The difference between them is first solution is add space to user input while second solution check that I don’t add last word or not. I want to know which one is better solution for this problem?

If there’re better solutions, please tell me.

Answer 1

I would write this:

std::vector<std::string> data;

std::copy(std::istream_iterator< std::string>(std::cin), 
          std::istream_iterator< std::string>(),
          std::back_inserter(data));

It is almost same as @K-ballo’s answer, except that I let std::copy read directly from input stream (i.e std::cin) rather than from std::stringstream.

Demo: http://www.ideone.com/f0Gtc

—

Or you could make use of vector’s constructor, avoiding std::copy altogether:

 std::vector<std::string> data(std::istream_iterator<std::string>(std::cin), 
                               std::istream_iterator<std::string>());

And you’re done! Demo : http://www.ideone.com/Szfes

If you find it difficult to read, then use this instead:

 std::istream_iterator<std::string> begin(std::cin), end;
 std::vector<std::string> data(begin, end);

Demo : http://www.ideone.com/PDcud