c++ - 带递归的可变参数函数

Question

我试图编写一个带有可变参数的递归函数来复制我的数据。但是这个函数只复制最后一个参数。我做错了什么？

这是输出:

13 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

12 0 0 0 0 0 0 0 0 0 0 0 

最好的问候。

#include <iostream>
#include <cstdint>
#include <cstring>
using namespace std;

void copy_data(unsigned char* ar, unsigned& offset, int data) {
    std::memcpy(ar + offset, (void*)&data, sizeof(data));
    offset += sizeof(data);
}

template<class... Args>
void copy_data(unsigned char* ar, unsigned& offset, int data, Args... args) {
    if ((sizeof...(Args)) == 0) {
        copy_data(ar, offset, data);
    }
    copy_data(ar, offset, args...);
}

void printf_data(const unsigned char* ar, int s) {
    for (int i = 0; i < s; ++i) {
        std::cout << (int)ar[i] << " ";
    }
    std::cout<<"\n";
}

int main() {
    unsigned char *arr0 = new unsigned char[16];
    unsigned char *arr1 = new unsigned char[12];

    int p0 = 10;
    int p1 = 11;
    int p2 = 12;
    int p3 = 13;

    unsigned offset = 0;

    copy_data(arr0, offset, p0, p1, p2, p3);

    offset = 0;
    copy_data(arr1, offset, p0, p1, p2);

    printf_data(arr0, 16);
    printf_data(arr1, 12);

    delete [] arr1;
    delete [] arr0;
    return 0;
}

更新:更正的功能

template <typename T>
void copy_data(unsigned char* ar, unsigned& offset, T data) {
    std::memcpy(ar + offset, (void*)&data, sizeof(data));
    offset += sizeof(data);
}

template <typename T, typename... Args>
void copy_data(unsigned char* ar, unsigned& offset, T data, Args... args) {
    copy_data(ar, offset, data);
    copy_data(ar, offset, args...);
}

Answer 1

递归仅在以下情况下输出任何内容:

if ((sizeof...(Args))==0) {
    copy_data(ar, offset, data);
}

这只会在您去除除最后一个参数之外的所有参数之后发生。

删除 if 子句。