foo.cc: In function 'int main()':
foo.cc:6:6: warning: statement has no effect [-Wunused-value]
     b==n/100;
     ~^~~~~~~
foo.cc:7:6: warning: statement has no effect [-Wunused-value]
     c==(n-b*100)/10;
     ~^~~~~~~~~~~~~~
foo.cc:8:6: warning: statement has no effect [-Wunused-value]
     d==n%10;
     ~^~~~~~
foo.cc:9:12: warning: 'd' is used uninitialized in this function [-Wuninitialized]
     cout<<d*100+c*10+b<<endl;
           ~^~~~
foo.cc:9:18: warning: 'c' is used uninitialized in this function [-Wuninitialized]
     cout<<d*100+c*10+b<<endl;
                 ~^~~
foo.cc:9:22: warning: 'b' is used uninitialized in this function [-Wuninitialized]
     cout<<d*100+c*10+b<<endl;
                      ^

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