C ++操作在“打包”数组 [英] C++ operating on "packed" arrays

问题描述

假设我有两个，例如 float 数组 a 和 b ， int 键数组 k 和模板 mySortByKey 我自己的函数，在单个数组上操作，像

Suppose that I have two, for example, float arrays a and b, an int key array k and a template mySortByKey function of my own, operating on a single array, something like

template<class T>
mySortByKey(int *k, T *a)

使用zip迭代器和某些类型的元组）使 mySort 同时在 a 和 b c

Is there a possibility (for example, using zip iterators and tuples of some sorts) to enable mySort operating simultaneously on a and b, so that they can be simultaneously ordered according to the key k?

推荐答案

我不认为你可以这样做。但是，您可以使用辅助数组的索引来完成类似的操作。

I don't think you can do that. However, you can accomplish something similar by the use of a helper array of indices.

int keys[ARRAY_SIZE];
float a[ARRAY_SIZE];
float b[ARRAY_SIZE];

// Fill up the contents of keys, a, and b

// Create an array of indices.
int indices[ARRAY_SIZE];
for ( int i = 0; i < ARRAY_SIZE; ++i )
   indices[i] = i;

// Sort the indices using keys.
mySortByKey(keys, indices);

// Now access the arrays a and b indirectly, using the sorted array
// of indices as an intermediate object.
for ( int i = 0; i < ARRAY_SIZE; ++i )
{
   float fa = a[indices[i]];
   float fb = b[indices[i]];
}

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