string line = "hello there 1234";

istringtream in(line);

string s, t, x;
int u;

in >> s >> t >> u;
if (in.fail())
  not enough input or 3rd not an int

in >> x;
if (! in.fail())
  error - extra thing on line

in.clear()



0: 53   3
1: 17     12
2: 29        15
3: 65           17
4: 12     17    65 29
5: 38                 38
6: 99                    45
7:  3  53                   53
8: 15        29    65          65
9: 45                    99       99

A[0] ... A[N-1]

b first thing not yet (known to be) in right place
s smallest seen so far in inner loop

     for (boundary = 0; boundary < N - 1; boundary += 1)
     { smallpos = boundary
       for (looking = boundary + 1; looking < N; looking += 1)
         if (A[looking] < A[smallpos])
           smallpos = looking;
       swap(A[smallpos], A[boundary]); }