Anonymous (?) initialization of a struct passed as an argument in C++03

Question

Say, I have

struct Foo
{
    char a;
    char b;
};

void bar(Foo foo);

What's the most succinct way to initialize a struct and pass it to the function? Ideally I would like to write something like

bar(Foo = {'a','b'});

What if Foo was a union?

UPD: My sincere apologies, the question was supposed to be in relation to C++03 only. Also, in this particular case, going away from POD is to be avoided (the code is for embedded system, ergo shorter bytecode is sought after). vonbrand, thanks for the C++11 answer.

In this case, I suspect that even for C++11 there will be ambiguity if the bar was overloaded. — NioBium, Mar 09 '14 at 07:24

vonbrand · Accepted Answer · 2021-02-21T14:26:15.250

5

In C++ 11 you can write:

bar({'a', 'b'});

or:

bar(Foo{'a', 'b'});

(see Stroustup's C++11 FAQ).

g++-4.8.2 accepts this without complaints only if you give it -std=c++11, clang++-3.3 gives an error unless -std=c++11

edited Feb 21 '21 at 14:26

answered Mar 08 '14 at 01:39

vonbrand

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Thank you. Please see the edit to the original post. – NioBium Mar 09 '14 at 07:26

score 1 · Answer 2 · answered Mar 08 '14 at 01:17

1

You could add a constructor to your struct. e.g.

struct Foo
{
    Foo(char a, char b) : a(a), b(b) {}
    char a;
    char b;
};

Then you could call your function

bar(Foo('a', 'b'));

If it was a union, you could have different constructors for the different types of the union.

answered Mar 08 '14 at 01:17

The Dark

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This is true but now your struct is no longer POD so it has huge ramifications. The C++11 way allows it to remain POD. – StilesCrisis Mar 08 '14 at 01:54

Anonymous (?) initialization of a struct passed as an argument in C++03

2 Answers2