省略号出现在模板函数的参数声明中(Ellipsis appears in a parameter declaration of a template function)

省略号出现在模板函数的参数声明中(Ellipsis appears in a parameter declaration of a template function)

这是来自cppreference的示例。 我不明白模式是如何扩展的。

template<typename ...Ts, int... N> void g(Ts (&...arr)[N]) {} int n[1]; g<const char, int>("a", n); // Ts (&...arr)[N] expands to // const char (&)[2], int(&)[1] Note: In the pattern Ts (&...arr)[N], the ellipsis is the innermost element, not the last element as in all other pack expansions.

问题1：什么是arr？

问题2：n是一个int数组，它与int ... N匹配吗？

问题3：为什么它可以扩展为const char（＆）[2]，int（＆）[1]

This is the example from cppreference. I don't understand how the pattern get expanded.

template<typename ...Ts, int... N> void g(Ts (&...arr)[N]) {} int n[1]; g<const char, int>("a", n); // Ts (&...arr)[N] expands to // const char (&)[2], int(&)[1] Note: In the pattern Ts (&...arr)[N], the ellipsis is the innermost element, not the last element as in all other pack expansions.

Question 1: what is arr?

Question 2: n is a int array, does it match to int...N?

Question 3: How come it can expand to const char (&)[2], int(&)[1]

最满意答案

而

template <typename ...Ts> void f(Ts&...arr);

大多相当于

template <typename T0, typename T1, .., typename TN> void f(T0& arr0, T1& arr1, .., TN& arrN);

任何N

以同样的方式，

template <typename ...Ts, int... Ns> void g(Ts (&...arr)[Ns]);

相当于

template <typename T0, typename T1, .., typename TN, int N0, int N1, .. int NN> void g(T0 (&arr0)[N0], T1 (&arr1)[N1], .., TN (&arrN)[NN]);

类型T (&)[N]是对大小为N C-数组的引用，其中元素为T类型

int n[1]; 通常类型为int [1] 。

"a"的类型为const char[2] （ {'a', '\0'} ）。

Whereas

template <typename ...Ts> void f(Ts&...arr);

is mostly equivalent to

template <typename T0, typename T1, .., typename TN> void f(T0& arr0, T1& arr1, .., TN& arrN);

for any N.

In the same way,

template <typename ...Ts, int... Ns> void g(Ts (&...arr)[Ns]);

would be equivalent to

template <typename T0, typename T1, .., typename TN, int N0, int N1, .. int NN> void g(T0 (&arr0)[N0], T1 (&arr1)[N1], .., TN (&arrN)[NN]);

and type T (&)[N] is a reference to C-array of size N with element of type T

int n[1]; is trivially of type int [1].

"a" is of type const char[2] ({'a', '\0'}).