How do I initialize this struct?

Question

Sorry for being not specific, but...

Suppose I have this struct:

struct OptionData
{
    Desc desc;
    bool boolValue;
    std::string stringValue;
    int intValue;
    double numberValue;
};

which I'm using this way:

OptionData isWritePatchesOptionData = {isWritePatchesDesc, {}, {}, {}, {}};

As I have lots of those options, I'd like to do s.t. like this:

<type_here> OptionDataList = {{}, {}, {}, {}};

so I can do:

OptionData isSeamCutOptionData = {isSeamCutDesc, OptionDataList};

but really on the spot I can't figure what type_here would be... Or maybe is not possible in this form... I mean, without creating an OptionDataList object into the OptionData struct... but that clearly would be redundant...

why not use a constructor?

Jaffa
– Jaffa

2020-03-09 12:55:27 +00:00
Commented Mar 9, 2020 at 12:55 — Jaffa
– Jaffa, Commented Mar 9, 2020 at 12:55

NathanOliver · Accepted Answer · 2020-03-09 13:00:28Z

2

Just provide default initializers. Using

struct OptionData
{
    Desc desc{};
    bool boolValue{};
    std::string stringValue{};
    int intValue{};
    double numberValue{};
};

Everything in the struct will be value initialized meaning objects with a constructor will be default constructed and objects without a constructor will be zero initialized.

This lets you write

OptionData isWritePatchesOptionData = {isWritePatchesDesc}; // same as using {isWritePatchesDesc, {}, {}, {}, {}};
// and
OptionData isSeamCutOptionData = {isSeamCutDesc};

and now all of the other members are in a default/zero state.

answered Mar 9, 2020 at 13:00

NathanOliver

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2 Comments

Kabu Over a year ago

I think this is the straighest. Also I could do: OptionData isWritePatchesOptionData = {isWritePatchesDesc, {}}; - but that probably result in indeterminated initialization for the struct members... but not sure.

NathanOliver Over a year ago

@Kabu That would work as well. Everything will still be value initialized so default for constructor and zero for non-constructors.

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