/in/foo.cc: In function 'int main()':
/in/foo.cc:11:21: warning: suggest parentheses around arithmetic in operand of '^' [-Wparentheses]
   for(int i=1;i<=j;i+2^i)
                    ~^~
/in/foo.cc:11:23: warning: for increment expression has no effect [-Wunused-value]
   for(int i=1;i<=j;i+2^i)
                    ~~~^~
/in/foo.cc:13:22: error: expected primary-expression before '^' token
   for(int i=2;i<=j;i+^i)
                      ^
/in/foo.cc:15:22: error: expected primary-expression before '^' token
   for(int i=4;i<=j;i+^i)
                      ^