How to declare constant's name.

       1) By using #define keyword :-

                                                     #include <iostream>
                                                     using namespace std;
                                                     #define ALL 20
                                                     #define SOME 39
                                                     int main ( )
                                                    {
                                                        int a;
                                                        a=ALL+SOME;
                                                        cout << a;
                                                        return 0;
                                                    }

       2) By using const keyword :-

                                                        #include <iostream>
                                                        using namespace std;
                                                        int main ( )
                                                      {
                                                         int a;
                                                         const int ALL = 22;
                                                         const int SOME = 30;
                                                         a= ALL+SOME;
                                                         cout << a;
                                                         return o;
                                                      }




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