How to Initialize a Member Array with an Initializer List in C 0x?

How to Initialize a Member Array with an Initializer List

In C 0x, you can initialize a member array with an initializer list as follows:

<code class="cpp">Foo f = {1,3};</code>

However, this code will not compile in g 4.6, resulting in the error:

incompatible types in assignment of ‘std::initializer_list<const int>&’ to ‘const int [2]’

To resolve this issue, you can use a variadic template constructor instead:

<code class="cpp">struct Foo {
    int x[2];
    template <typename... T>
    Foo(T... ts) : x{ts...} {}
};

int main() {
    Foo f1(1, 2); // OK
}</code>

Alternatively, you can skip initialization and fill the array in the function body if you can live without constness:

<code class="cpp">struct Foo {
    int x[2];
    Foo(std::initializer_list<int> il) {
        std::copy(il.begin(), il.end(), x);
    }
};</code>

While this latter method allows you to initialize the array with an initializer list, it does not provide compile-time bounds checking like the variadic template constructor approach.

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