How to initialize whole array to single element in class constructor in c++

Question

Hi I am looking to initalize whole array to single element in constructor of class.I have tried this solution but I am getting this errror.

1>C:\Users\Ahmad Mustafa Anis\source\repos\ciruclar queue\Source.cpp(8,8): error C2590: 'sig': only a constructor can have a base/member initializer list
1>Done building project "ciruclar queue.vcxproj" -- FAILED.

My code is

class CircularQueue {
public:
    int dataItems[10];
    sig() : dataItems{0, 0, 0, 0, 0, 0, 0, 0, 0, 0} { }

};

I have Visual Studio 2019, I guess c++ version in it is cpp17. If there is someway I can add a constructor and assign whole array to 0 without for loop or explicitly element by element, like this constructor


CircularQueue() {
        dataItems = { 0 };
    }

or this one

CircularQueue() {
        dataItems =  0 ;
    }

In both case my error is

error C3863: array type 'int [10]' is not assignable

the method sig() is not a Constructor. You can only use initializer lists with Constructors. — Flo
– Flo, Commented Jun 13, 2020 at 12:05

김선달 · Accepted Answer · 2020-06-13 12:03:45Z

2

If you want to initialize all values with 0

CircularQueue() : dataItems{} {}

Or,

CircularQueue() : dataItems{0,0,0,0,0,0,0,0,0,0} {}

If the array is too long, you can do this. It is not initializing. It's assigning after initialization.

CircularQueue() {
    std::fill(dataItems, dataItems+10, 3); //3 for example
}

answered Jun 13, 2020 at 12:03

김선달

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5 Comments

Flo Over a year ago

Its probably more safe to use dataItems+sizeof(dataItems).

김선달 Over a year ago

@Flo No sizeof(dataItems) is 40.

Ahmad Anis Over a year ago

This works. I need to assign 0 so the first technique is useful for me. Thanks.

Flo Over a year ago

@김선달 True, It would need to be divided by sizeof(int)

cigien Over a year ago

fill can use begin, end, so if the size is changed, it only needs to be done in one place.

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