/in/foo.cc: In function 'int two_fen_cha_zhao(int)':
/in/foo.cc:11:12: warning: 'right' may be used uninitialized in this function [-Wmaybe-uninitialized]
   mid=(left+right)/2;
       ~~~~~^~~~~~~
/in/foo.cc:15:9: warning: 'left' may be used uninitialized in this function [-Wmaybe-uninitialized]
  return left;
         ^~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:11:12: warning: 'right' may be used uninitialized in this function [-Wmaybe-uninitialized]
   mid=(left+right)/2;
       ~~~~~^~~~~~~
/in/foo.cc:8:11: note: 'right' was declared here
  int left,right,mid;
           ^~~~~
/in/foo.cc:50:12: warning: 'left' may be used uninitialized in this function [-Wmaybe-uninitialized]
    ans[pos]=num[i];
    ~~~~~~~~^~~~~~~