What does (void) sizeof (0[array]) mean?

Question

I come across the following code, which returns the size of a C style array.

template <typename Type, int N>
int GetArraySize(Type (&array)[N])
{
    (void) sizeof (0[array]);
    return N;
}

The templated part seems to have been already explained in this question.

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But still, I don't understand what is the utility of the sizeof line. Any ideas? Some suggest that it is to avoid unused variable warning, but a simpler #pragmacould have been used, right?

Moreover, will this piece of code be effective in any situation? Aren't there any restrictions?

Answer 1

I think the purpose of the line is to silent unused variable warning. The simpler would be to omit parameter name

template <typename Type, int N>
int GetArraySize(Type (&)[N])
{
    return N;
}