如何在C++中的类内创建动态2D数组（） _C++开发

假设我们要为Graph创建一个类。该类存储图的邻接矩阵表示。因此, 我们的类结构如下所示。

class Graph { int V; int adj[V][V]; //This line doesn't work/* Rest of the members */ }; int main() { }

【如何在C++中的类内创建动态2D数组（）】输出：

error: invalid use of non-static datamember 'Graph::V'.

即使我们将V设为静态, 也会出现错误"数组边界不是整数常量"
C ++不允许在大小不恒定的类中创建堆栈分配的数组。因此, 我们需要动态分配内存。下面是一个简单的程序, 用于显示如何使用带有邻接矩阵表示形式的Graph类在C ++类中动态分配2D数组。

//C++ program to show how to allocate dynamic 2D //array in a class using a Graph example. #include< bits/stdc++.h> using namespace std; //A Class to represent directed graph class Graph { int V; //No. of vertices//adj[u][v] would be true if there is an edge //from u to v, else false bool **adj; public : Graph( int V); //Constructor//function to add an edge to graph void addEdge( int u, int v){ adj[u][v] = true ; } void print(); }; Graph::Graph( int V) { this -> V = V; //Create a dynamic array of pointers adj = new bool * [V]; //Create a row for every pointer for ( int i=0; i< V; i++) { //Note : Rows may not be contiguous adj[i] = new bool [V]; //Initialize all entries as false to indicate //that there are no edges initially memset (adj[i], false , V* sizeof ( bool )); } }//Utility method to print adjacency matrix void Graph::print() { for ( int u=0; u< V; u++) { for ( int v=0; v< V; v++) cout < < adj[u][v] < < " " ; cout < < endl; } }//Driver method int main() { //Create a graph given in the above diagram Graph g(4); g.addEdge(0, 1); g.addEdge(0, 2); g.addEdge(1, 2); g.addEdge(2, 0); g.addEdge(2, 3); g.addEdge(3, 3); g.print(); return 0; }

输出：