指向多维数组的指针

本文介绍了指向多维数组的指针的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我有2个数组，分别是int a [10] [20]和int b [10] [20].我想为一个或另一个数组创建一个点并读取数据.在一种情况下，我可能需要数据，而在另一种情况下，我可能需要b数据.

I have2 arrays, int a[10][20] and int b[10][20]. I want to create a point toone or the otherarray and read the data. In one condition I may want a data and the other I might want b data.

示例.

int ** ptr;

int **ptr;

ptr =& a; //不起作用，无法找出如何为现有二维数组分配指针

ptr=&a; // doesn''t work can''t figure out how to assign a pointer to and existing 2 dimension array

推荐答案

在C ++中指向多维​​数组的指针很棘手.通常，您必须指定每个维度的实际容量，这意味着一个指针不能用于两个不同大小的数组.如果您真的想要一个指针，我建议您制作一个单一维度的数组，然后就可以计算索引以使用多个维度.会像这样: Pointers to multidimensional arrays in C++ is tricky business. Most often, you have to specify the actual capacity of each dimension, which means one pointer cannot be used for two different sized arrays. If you really want a pointer, I suggest making a single dimension array and then you can just calculate the index to use multiple dimensions. Would go something like this: int wide = 640; int tall = 480; int * pArray = new int[wide * tall]; int x; int y; int yOffset; int offset; for(y = 0; y < tall; y++) { yOffset = y * wide; for(x = 0; x < wide; x++) { offset = yOffset + x; // Use pointer arithmetic to assign element at (x,y). *(pArray + offset) = CalculateSomething(x, y); } }

好吧，它们要么是相同的数组，要么是两个不同的数组.您可以编写一个类来交换它查找的指针，但是不能有两个数组也都是相同的数组，但有时是这样.

Well, they are either the same array, or two different arrays. You could write a class that swaps which pointer it looks up, but you can''t have two arrays that are also the same array, but only sometimes.

好吧，我尝试过，但是我完全困惑为什么它不起作用(请注意奇怪的错误，在其所在行上方的注释中): Well, I tried, but I''m completely baffled as to why this doesn''t work (note the strange error, which is in a comment above the line it occurs at): // Interface to access array functions (get value, set value). template<class T> class IArrayHolder{ public: virtual T GetVal(int x, int y) = 0; //...Set value... }; // Class to wrap an array. template<class T, class S> class ArrayHolder: public IArrayHolder<S> { private: T multiArray; public: ArrayHolder(T val){ // error C2440: '=' : cannot convert from 'int [][20]' to 'int [][20]' multiArray = val; } S GetVal(int x, int y){ return multiArray[x][y]; }; }; // Some function that uses multiple multi-dimension arrays. System::Void SomeFunction(){ int x[10][20]; int y[20][30]; IArrayHolder<int> * xInterface; xInterface = new ArrayHolder<int[][20], int>(x); IArrayHolder<int> * yInterface; yInterface = new ArrayHolder<int[][30], int>(y); }; // Some function that accepts a 2D array. System::Void AnotherFunction(IArrayHolder<int> * arrayHolder){ int val = arrayHolder->GetVal(20, 20); };

您找出该错误，然后就可以解决了.如果不是这样，也许您应该只将数组值复制到2D向量中，然后使用它.另外，我对void指针没有太多的经验，但是它们显然可以指向任何对象的地址，因此您可以尝试使用它们.

You figure out that error, and you''ve go your solution. If not, perhaps you should just copy the array values to a 2D vector and use that instead. Also, I don''t have much experience with void pointers, but they can apparently point to the address of anything, so you might try working with those.