我可以为数组的所有成员添加一个值吗 [英] Can I add a value to all members of an Array

问题描述

STL 中是否有一种算法可以一次将相同的值添加到数组的所有成员中?

Is there an algorithm in STL that can add at once the same value to all the members of an array?

例如:

KnightMoves moveKnight(int currentPossition_x, int currentPossition_y)
{
    array<int , 8> possibleMoves_x = { -2 , -2 , -1 , -1 ,  1 , 1 , 2 ,  2 };
    array<int , 8> possibleMoves_y = { -1 ,  1 , -2 ,  2 , -2 , 2 , -1 , 1 };

    for (auto it = possibleMoves_x.begin(); it != possibleMoves_x.end(); it++)
    {
        array <int, 8> newTempKnightPoss_x = currentPossition_x + possibleMoves_x;

        array <int, 8> newTempKnightPoss_y = currentPossition_y + possibleMoves_x;
    }

}

我可以做这样的事情，但我希望有更好的解决方案

I could do something like this but i was hopping there is a better solution

KnightMoves moveKnight(int currentPossition_x, int currentPossition_y)
{
   array<int , 8> possibleMoves_x = { -2 , -2 , -1 , -1 ,  1 , 1 , 2 ,  2 };
   array<int , 8> possibleMoves_y = { -1 ,  1 , -2 ,  2 , -2 , 2 , -1 , 1 };

   for (auto it = possibleMoves_x.begin(); it != possibleMoves_x.end(); it++)
   {
       *it = *it  +currentPossition_x;

   }
   for (auto it = possibleMoves_y.begin(); it != possibleMoves_y.end(); it++)
   {
       *it = *it + currentPossition_y;

   }
}

得到的结果是2个数组，每个元素是一个元素加上一个常数值；

The axpepted results are 2 arrays which each element is the element plus a constant value;

推荐答案

如果你有 C++11 你可以使用 基于范围的 for 循环:

If you have C++11 you can use the range-based-for loop:

KnightMoves moveKnight(int currentPossition_x, int currentPossition_y){
    array<int , 8> possibleMoves_x = { -2 , -2 , -1 , -1 ,  1 , 1 , 2 ,  2 };
    array<int , 8> possibleMoves_y = { -1 ,  1 , -2 ,  2 , -2 , 2 , -1 , 1 };

    for(auto& i : possibleMoves_x){ i += currentPossition_x; }
    for(auto& i : possibleMoves_y){ i += currentPossition_y; }
}

在 C++11 之前，您可以使用 std::for_each:

Before C++11 you can use std::for_each:

struct adder{
    adder(int val): v{val}{}
    void operator()(int& n) { n += v; }
    int v;
};

KnightMoves moveKnight(int currentPossition_x, int currentPossition_y){
    array<int , 8> possibleMoves_x = { -2 , -2 , -1 , -1 ,  1 , 1 , 2 ,  2 };
    array<int , 8> possibleMoves_y = { -1 ,  1 , -2 ,  2 , -2 , 2 , -1 , 1 };

    std::for_each(possibleMoves_x.begin(), possibleMoves_x.end(), 
                  adder(currentPossition_x));
    std::for_each(possibleMoves_y.begin(), possibleMoves_y.end(),
                  adder(currentPossition_x));
}

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