c++ - 如何创建二进制文字数组

Question

我希望我的代码中的二进制消息数组作为文字。消息非常小，所以我认为使用“二进制”字面量是最简单的。但是要怎么做呢？

我试过这段代码:

struct binary_message
{
    binary_message(int size, unsigned char* bytes) : size_(size), bytes_(bytes) {}
    int size_;
    unsigned char* bytes_;
};

binary_message messages[] = {
    { 3, { 0x1, 0x2, 0x3 } },
    { 2, { 0x1, 0x2 } },
    { 1, { 0x1 } }
};

使用 Visual Studio 2013 C++ 编译器时出现错误:

error C2440: 'initializing' : cannot convert from 'initializer-list' to 'binary_message'. No constructor could take the source type, or constructor overload resolution was ambiguous

使用 g++ 我得到:

>g++ main.cpp
main.cpp:13:1: warning: extended initializer lists only available with -std=c++0x or -std=gnu++0x [enabled by default]
main.cpp:13:1: warning: extended initializer lists only available with -std=c++0x or -std=gnu++0x [enabled by default]
main.cpp:13:1: warning: extended initializer lists only available with -std=c++0x or -std=gnu++0x [enabled by default]
main.cpp:13:1: error: could not convert '{3, {1, 2, 3}}' from '<brace-enclosed initializer list>' to 'binary_message'
main.cpp:13:1: error: could not convert '{2, {1, 2}}' from '<brace-enclosed initializer list>' to 'binary_message'
main.cpp:13:1: error: invalid conversion from 'int' to 'unsigned char*' [-fpermissive]
main.cpp:4:2: error:   initializing argument 2 of 'binary_message::binary_message(int, unsigned char*)' [-fpermissive]

如果我使用 g++ -std=c++0x main.cpp 我仍然得到:

main.cpp:13:1: error: could not convert '{3, {1, 2, 3}}' from '<brace-enclosed initializer list>' to 'binary_message'
main.cpp:13:1: error: could not convert '{2, {1, 2}}' from '<brace-enclosed initializer list>' to 'binary_message'
main.cpp:13:1: error: invalid conversion from 'int' to 'unsigned char*' [-fpermissive]
main.cpp:4:2: error:   initializing argument 2 of 'binary_message::binary_message(int, unsigned char*)' [-fpermissive]

我该如何解决这个问题？

更新

我猜你的意思是这样的？

#include <vector>
#include <iostream>

struct binary_message
{
    binary_message(std::initializer_list<unsigned char> data) : bytes_(data) {}
    std::vector<unsigned char> bytes_;
};

int main()
{
    binary_message messages[] = {
            { 0x1, 0x2, 0x3 },
            { 0x1, 0x2 },
            { 0x1 }
    };

    binary_message msg1 = messages[0];

    return 0;
}

Answer 1

如果你想使用初始化列表来构造你的对象，你需要一个初始化列表构造函数。您当前的构造函数接受缓冲区的大小和缓冲区，但 { 3, { 0x1, 0x2, 0x3 } } 与此完全不同 - 它是一个数字和初始化列表的初始化列表。

要正确使用初始化列表，您的类和构造函数应该大致如下所示:

binary_message( std::initializer_list<int> data) : data(data) {}
...
std::vector<int> data;

而且您根本不会使用 size - vector 的大小会告诉您。