Warning: comparison between signed and unsigned integer expressions

c.vimだとwarningでも\rrが弾かれてしまうので、、、
こちらを参照。

vector<int> s;
 for (int i = 0; i<(int)s.size(); ++i)    // cast
   s[i]++;
 

vector<int> s;
 for (unsigned int i = 0; i<s.size(); ++i) // unsigned int
   s[i]++;