Sure you could do that.

http://www.cplusplus.com/reference/string/string/
But perhaps the find method (in a loop) to step over a number of spaces in the line would perhaps be more reliable.

Why would you need a 2D array when you're only interested in the 2nd line?
Just read the first line and throw it away, there's no need to store it.

Try some ideas and see what happens