Using const
Hi
Hopefully someone will be able to guide me in the usage of const.
I have a base class Parent, which has a pure virtual class function to be defined in the concrete child class Child. The class function Function() is const and takes two arguments, 1) a const array by reference: Array, and 2) a non-const vector by reference Vector. This is given as part of the established code structure.
My job is to write a child class of Parent to perform a certain task, so part of this is to define Function(). In Function() I want to process the values of Array to see if it meets a certain criteria. So in order to do so, I introduced a working variable say,
The first problem is that because Function() is const, I can't change the value of Indicator within Function(). So then I moved the processing code to a non-const function ProcessingFn().
But when I call ProcessingFn() within Function() to do the processing, I get the error on ProcessingFn():
So I thought maybe this is an issue with trying to pass the const Array into ProcessingFn() (which is a non-const function). However when I make a copy of Array in Function() (literally creating another array and looping through all values), and using the copy as the argument in ProcessingFn(), the error remains.
How do you call a non-const function within a const function? (If that is the right question to ask).
As always, any and all help much appreciated.
Hopefully someone will be able to guide me in the usage of const.
I have a base class Parent, which has a pure virtual class function to be defined in the concrete child class Child. The class function Function() is const and takes two arguments, 1) a const array by reference: Array, and 2) a non-const vector by reference Vector. This is given as part of the established code structure.
My job is to write a child class of Parent to perform a certain task, so part of this is to define Function(). In Function() I want to process the values of Array to see if it meets a certain criteria. So in order to do so, I introduced a working variable say,
bool Indicator to record when the ith element of Array meets the criteria.The first problem is that because Function() is const, I can't change the value of Indicator within Function(). So then I moved the processing code to a non-const function ProcessingFn().
But when I call ProcessingFn() within Function() to do the processing, I get the error on ProcessingFn():
| The object has type qualifiers that are not compatible with the member function. |
So I thought maybe this is an issue with trying to pass the const Array into ProcessingFn() (which is a non-const function). However when I make a copy of Array in Function() (literally creating another array and looping through all values), and using the copy as the argument in ProcessingFn(), the error remains.
How do you call a non-const function within a const function? (If that is the right question to ask).
As always, any and all help much appreciated.
| pzling wrote: |
|---|
| How do you call a non-const function within a const function? |
You can't call a the object's non-const member functions from inside a const member function.
If you want Function() to modify member variables, why is it const to begin with?
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