如何在C ++中创建多维网格结构 [英] How to create a multidimensional grid structure in C++

问题描述

如果我事先不知道维数，是否可以在C ++中创建多维网格结构.

例如，我想在内存中存储一​​些k维数据，但是我不知道k在编译时的值，它是在运行时作为用户输入获得的.在C ++中有什么方法可以做到这一点?

在此先感谢您.

Is there anyway to create a multidimensional grid structure in C++ if I don''t know the number of dimensions in advance.

For example I want to store some k dimensional data in the memory, but I don''t know the value of k at compile time, it is obtained as a user input at run time. Is there any way of doing this in C++ ?

Thanks in advance.

推荐答案

有动态内存分配，因此您可以这样做.请注意，随着k的增加，您很快就会用完内存.
:)

There''s dynamic memory allocation, hence you can do that. Beware, as k increases, you will quickly run out of memory.
:)

是的，您当然可以在C ++中做到这一点.

不，没有内置的东西可以帮您完成现成的事情.

正如CPallini指出的那样，它将需要使用动态内存分配.

最近有一个相关的问题.基于此，这是一个可能的起点.当心这是现成的，不要尝试编译.它不包含错误检查.它甚至可能包含明显的错误.

Yes, you can certainly do that in C++.

No, there isn''t anything built in that will do it for you ready made.

As CPallini indicated, it will require the use of dynamic memory allocation.

There was a somewhat related question recently. Based on that, here is a possible starting point. Beware this is off-the-cuff with no attempt to compile. It contains no error checking. It may even contain glaringly obvious errors.

template<typename T>
class multiDimArray
{
public:
    multiDimArray( const std::vector<size_t> &dimensions ) :
        dimensions_( dimensions ), pContents(NULL);
    {
        size_t size = 1;
        std::vector<size_t>::const_iterator dimIter = dimensions_.begin();
        for ( ; dimIter != dimensions_.end(), ++dimIter )
        {
            size *= *dimIter;
        }
        pContents = new T[ size ];
    }

    ~multiDimArray( )
    {
        delete [] pContents;
    }

    T& operator()( const std::vector<size_t> &indicies )
    {
        std::vector<size_t>::const_iterator indexIter = indicies.begin();
        std::vector<size_t>::const_iterator dimIter = dimensions_.begin();

        // calculate offset into linear array
        size_t offset = 0;
        ++dimIter;  // first dimension isn''t used in the calculation
        for ( ; dimIter != dimensions_.end(); ++dimIter, ++indexIter )
        {
            offset += *indexIter;
            offset *= *dimIter;
        }
        offset += *indexIter;  // add last index value

        return *(pContents + offset);
    }

    std::vector<size_t>size_type NumberOfDimensions() const
    {
        return dimensions_.size();
    }

private:
    T *pContents;
    std::vector<size_t> dimensions_;
};

类似的声音基本线性代数库 [

Sounds like Basic Linear Algebra Library[^] fits the bill, supports sparse matrices.

Regards
Espen Harlinn

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