c++ - read input separated by whitespace(s) or newline...?

Question

I'm grabbing input from a standard input stream. Such as,

1 2 3 4 5

or

1
2
3
4
5

I'm using:

std::string in;
std::getline(std::cin, in);

But that just grabs upto the newline, correct? How can I get input whether they are separated by newline OR whitespace(s) using only iosteam, string, and cstdlib?

Answer 1

Just use:

your_type x;
while (std::cin >> x)
{
    // use x
}

operator>> will skip whitespace by default. You can chain things to read several variables at once:

if (std::cin >> my_string >> my_number)
    // use them both

getline() reads everything on a single line, returning that whether it's empty or contains dozens of space-separated elements. If you provide the optional alternative delimiter ala getline(std::cin, my_string, ' ') it still won't do what you seem to want, e.g. tabs will be read into my_string.

Probably not needed for this, but a fairly common requirement that you may be interested in sometime soon is to read a single newline-delimited line, then split it into components...

std::string line;
while (std::getline(std::cin, line))
{
    std::istringstream iss(line);
    first_type first_on_line;
    second_type second_on_line;
    third_type third_on_line;
    if (iss >> first_on_line >> second_on_line >> third_on_line)
        ...
}