/in/foo.cc: In function 'int main()':
/in/foo.cc:20:17: error: 'strlen' was not declared in this scope
  for(int i=0;i<=strlen(st);i++)
                 ^~~~~~
/in/foo.cc:20:17: note: suggested alternative: 'mbrlen'
  for(int i=0;i<=strlen(st);i++)
                 ^~~~~~
                 mbrlen
/in/foo.cc:23:12: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   if(c>='a'&&c<='z'||c>='A'&&c<='Z')
      ~~~~~~^~~~~~~~
/in/foo.cc:31:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(int i=0;i<index.size();i++)
                ~^~~~~~~~~~~~~
/in/foo.cc:49:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<index.size();i++)
              ~^~~~~~~~~~~~~