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When u code, your source code is distributed over multiple files. You compile them separately and link the object code. Now it may happen for instance say you have one variable that has been defined in one file and is used to keep count. Now in some other file you need to have a count. but then if you are including...

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Well , you can return anything from a function right from a pointer to any built in data type.. but you cannot return a reference to any of the user defined datatype as the cout will not know what you have defined as the definition for aything can vary from person to person...