使用数组作为地图的价值：不能看到的错误 [英] Using array as map value: Cant see the error

问题描述

我试着去创建一个地图，其中关键是int，值是一个数组

Im trying to create a map, where the key is an int, and the value is an array

int red[3]  = {1,0,0};
int green[3] = {0,1,0};
int blue[3]     = {0,0,1};

    std::map<int, int[3]> colours;

colours.insert(std::pair<int,int[3]>(GLUT_LEFT_BUTTON,red)); //THIS IS LINE 24 !
colours.insert(std::pair<int,int[3]>(GLUT_MIDDLE_BUTTON,blue));
colours.insert(std::pair<int,int[3]>(GLUT_RIGHT_BUTTON,green));

然而，当我尝试编译此code，我碰到下面的错误。

However, when I try to compile this code, I get the following error.

g++ (Ubuntu 4.4.1-4ubuntu8) 4.4.1

 In file included from /usr/include/c++/4.4/bits/stl_algobase.h:66,
                 from /usr/include/c++/4.4/bits/stl_tree.h:62,
                 from /usr/include/c++/4.4/map:60,
                 from ../src/utils.cpp:9:
/usr/include/c++/4.4/bits/stl_pair.h: In constructor ‘std::pair<_T1, _T2>::pair(const _T1&, const _T2&) [with _T1 = int, _T2 = int [3]]’:
../src/utils.cpp:24:   instantiated from here
/usr/include/c++/4.4/bits/stl_pair.h:84: error: array used as initializer
/usr/include/c++/4.4/bits/stl_pair.h: In constructor ‘std::pair<_T1, _T2>::pair(const std::pair<_U1, _U2>&) [with _U1 = int, _U2 = int [3], _T1 = const int, _T2 = int [3]]’:
../src/utils.cpp:24:   instantiated from here
/usr/include/c++/4.4/bits/stl_pair.h:101: error: array used as initializer
In file included from /usr/include/c++/4.4/map:61,
                 from ../src/utils.cpp:9:
/usr/include/c++/4.4/bits/stl_map.h: In member function ‘_Tp& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](const _Key&) [with _Key = int, _Tp = int [3], _Compare = std::less<int>, _Alloc = std::allocator<std::pair<const int, int [3]> >]’:
../src/utils.cpp:30:   instantiated from here
/usr/include/c++/4.4/bits/stl_map.h:450: error: conversion from ‘int’ to non-scalar type ‘int [3]’ requested
make: *** [src/utils.o] Error 1

我真的不能看到错误所在。或者即使有一个错误。

I really cant see where the error is. Or even if there's an error.

任何帮助（请说明理由，以帮助我避免这个错误）将AP preciated。

Any help (please include an explanation to help me avoid this mistake) will be appreciated.

推荐答案

您无法通过这样的值复制阵列。

You can't copy arrays by value like that.

下面有几种解决方案，但我建议＃4你的需要：

Here are several solutions, but I recommend #4 for your needs:

1）使用的std ::矢量而不是数组

2）使用地图指针到3个元素的数组。

2) Use a map of pointers to arrays of 3 elements.

int red[3]  = {1,0,0};
int green[3] = {0,1,0};
int blue[3]     = {0,0,1};
std::map<int,int(*)[3]> colours;
colours.insert(std::pair<int,int(*)[3]>(GLUT_LEFT_BUTTON,&red));
colours.insert(std::pair<int,int(*)[3]>(GLUT_MIDDLE_BUTTON,&blue));
colours.insert(std::pair<int,int(*)[3]>(GLUT_RIGHT_BUTTON,&green));
//Watch out for scope here, you may need to create the arrays on the heap.

3）使用提振元组，而不是3个元素的数组

3) Use boost tuples instead of arrays of 3 elements.

4）而不是使用一个数组作出新的结构是需要3个要素。使地图。或包装你的阵列中的结构，而且也可以工作。

4) Instead of using an array make a new struct that takes 3 elements. Make the map. Or wrap your array in a struct and that will work too.

struct Triple
{
    int color[3];
};

 //Later in code
Tripple red = {1, 0, 0}, green = {0, 1, 0}, blue = {0, 0, 1};
std::map<int,Triple> colours;
colours.insert(std::pair<int,Triple>(GLUT_LEFT_BUTTON,red));
colours.insert(std::pair<int,Triple>(GLUT_MIDDLE_BUTTON,blue));
colours.insert(std::pair<int,Triple>(GLUT_RIGHT_BUTTON,green));

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