enum and overloading operator<<

Consider the enumeration type

enum Colors {red, blue, green yellow, violet};

Implement the overloaded operator << that outputs the value of a Colors object as an enumeration value.

ostream &operator<< (ostream &ostr, const Colors &obj);

Can you help me with this part

Like for example

Code:

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if ( obj == red ) cout << "red";

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I think I just asked this question in my thread, only a little more elaborately...