Operator overloading

Clicky

Thanks.

Another quick question:


double& operator() (unsigned row, unsigned col); ← subscript operators often come in pairs
double operator() (unsigned row, unsigned col) const;


Any particular reason for the second one? I normally do, do operators in pairs but one is of the new data type and the other is an existing one

One of them is const, the other isn't. The data members of a const object are treated as const and only const functions of the object are allowed to be called. The two versions of the operator are to allow the returned value (which is a reference to a value inside the object) to be altered when the object is const and to still allow the value to be accessed (but not altered) when the object is const.

For primitive types and small objects you can return a copy of the data for the const version. For more complicated types where there may be more overhead involved with copying the const version usually returns a const reference.

If you are dealing with fixed-sized vectors & matrices (2/3/4d) then you might be interested in this

Quote:

Original post by Alexistran Thanks. Another quick question: double& operator() (unsigned row, unsigned col); ← subscript operators often come in pairs double operator() (unsigned row, unsigned col) const; Any particular reason for the second one?

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Yes.
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