在 C++ 中访问矩阵时崩溃
我正在尝试创建一个二维数组来表示加权图。为了制作矩阵，我制作了一个数组数组，如下面的构造函数所示。该矩阵将存储连接两个节点的边的权重。例如，graph[1][2] 将存储点 1 和 2 之间的边的权重。
Weighted_graph::Weighted_graph( int n ):vertices(n){
double **graph= new double *[vertices];
nodeDegree=new int [n];
edges=0;
for (int c=0;c<vertices;c++)
{
graph[c] = new double[vertices];
nodeDegree[c]=0;
for (int d=0;d<vertices;d++)
{
graph[c][d]=INF;
}
}
}
图形定义为 double **graph;
这似乎一直有效，直到我尝试访问该变量来自其他函数的图表，此时程序崩溃。 （INF 在代码中进一步定义）。
I'm trying to create a 2D array to represent a weighted graph. To make the matrix I am making an array of arrays, as shown in the constructor below. This matrix will store the weight of the edges connecting two nodes. For example graph[1][2] would store the weight of the edge between points 1 and 2.
Weighted_graph::Weighted_graph( int n ):vertices(n){
double **graph= new double *[vertices];
nodeDegree=new int [n];
edges=0;
for (int c=0;c<vertices;c++)
{
graph[c] = new double[vertices];
nodeDegree[c]=0;
for (int d=0;d<vertices;d++)
{
graph[c][d]=INF;
}
}
}
with graph defined as double **graph;
This seems to work until I try to access the variable graph from other functions at which point the program crashes. (INF is properly defined further down in the code).
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我认为您正在引用您正在构造的对象的图形成员。然而，graph 在那里被声明为局部变量。
I presume you are referencing the graph member of the object you are constructing. However, graph is declared as a local variable there.
这一切都与范围有关，因为您在一个函数中可以重复使用变量名，但这个变量只能在讲师中访问。删除构造函数中图表前面的 double**。
It's all about scope, because you are in a function you can re-use a variable name, but this one is only accessible in the instructor. Remove the double** from in front of graph in the constructor.
不要重新发明轮子。使用 boost::multi_array。
Don't reinvent the wheel. Use boost::multi_array.