/in/foo.cc: In function 'int sum(int, int)':
/in/foo.cc:10:9: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
  return ans;
         ^~~
/in/foo.cc: In function 'void case1()':
/in/foo.cc:24:17: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
    cout<<sum(l,r)<<endl; 
                 ^
/in/foo.cc: In function 'void setup_ta()':
/in/foo.cc:68:8: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
   ta[i]=sum(i-get_lowbits(i),i);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:68:8: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
   ta[i]=sum(i-get_lowbits(i),i);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
/in/foo.cc:6:6: note: 'ans' was declared here
  int ans,p=l;
      ^~~