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sizeof... operator

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Queries the number of elements in a parameter pack.

Contents

[edit] Syntax

sizeof...( parameter_pack ) (since C++11)

Returns an object of type std::size_t.

[edit] Explanation

Returns the number of elements in a parameter pack.

[edit] Keywords

sizeof

[edit] Example

#include <iostream>
 
template<class... Args>
std::size_t f()
{
    return sizeof...(Args);
}
 
int main()
{
    std::cout << f<>() << '\n'
              << f<int>() << '\n'
              << f<char, int, double>() << '\n';
}

Output:

0
1
3

[edit] See also