/in/foo.cc: In function 'int main()':
/in/foo.cc:6:14: warning: comparisons like 'X<=Y<=Z' do not have their mathematical meaning [-Wparentheses]
  int x,n,k;(1<=x<=n);//x为小明心中选定的整数 
             ~^~~
/in/foo.cc:14:10: warning: 'bigger' may be used uninitialized in this function [-Wmaybe-uninitialized]
    cout<<bigger<<endl;
          ^~~~~~
/in/foo.cc:16:10: warning: 'smaller' may be used uninitialized in this function [-Wmaybe-uninitialized]
    cout<<smaller<<endl;
          ^~~~~~~