最简单的二维数组，使用G ++，有一个可变尺寸的？ [英] Simplest 2D array, using g++, with one variable dimension?

问题描述

我想作一个这样的数组：

I would like to make an array like this:

double array[variable][constant];

只有第一尺寸是可变的。一个变量声明这是第一个维度给出了初始化错误。有没有一种简单的方法来使用指针或其他基本类型做到这一点？

Only the first dimension is variable. Declaring this with a variable as the first dimension gives initialization errors. Is there a simple way to do this with pointers or other basic types?

推荐答案

您可以做这样的事情，但它不是一个真正的二维数组。它是基于内部一个多维数组必然与规则线性的总体思路，对尺寸（N，M），你有一个数组： array2d [I，J] = array1d [J +我* M]

You could do something like that, but it is not a true 2D array. It is based on the general idea that internally a multiple dimension array is necessarily linear with the rule that for an array of dimensions (n, m) you have : array2d[i, j] = array1d[j + i*m]

#include "iostream"

using namespace std;

class dynArray {
private:
    double *array;
    int dim2;
public:
    dynArray(int variable, int constant) {
        array = new double[variable * constant];
    dim2 = constant;
    }
    ~dynArray() {
        delete array;
    }

    double value(int i, int j) {
        return array[j + i * dim2];
    }

    double *pt(int i, int j) {
        return array + j + i * dim2;
    }
};

int main(int argc, char*argv[]) {
    dynArray d(3,4);
    *d.pt(2,3) = 6.;
    cout << "Result : " << d.value(2,3) << endl;
    return 0;
}

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