foo.cc: In function 'int main()':
foo.cc:8:11: warning: comparison of constant '100' with boolean expression is always true [-Wbool-compare]
  while(1<x<100)
        ~~~^~~~
foo.cc:8:9: warning: comparisons like 'X<=Y<=Z' do not have their mathematical meaning [-Wparentheses]
  while(1<x<100)
        ~^~