/in/foo.cc: In function 'int main()':
/in/foo.cc:46:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < v.size(); i++)
                     ~~^~~~~~~~~~
/in/foo.cc: In function 'char Lower(char, char*, int)':
/in/foo.cc:17:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'char Higher(char, char*, int)':
/in/foo.cc:29:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^