bad_alloc error...

[jyothiusha]

terminate called after throwing an instance of 'std::bad_alloc'
what(): St9bad_alloc
Aborted


could anyone help me in this?

//mst.cpp
#include <iostream>
#include <fstream>
#include "Graph.h"
#include "LList.h"
#include "Edge.h"
//#include "Prim.h"
#include "Heap.h"
#include "Kruskal.h"
using std::cout;
using std::cerr;
using std::endl;
using std::exit;
using std::ifstream;
using std::cin;
 
main (int argc, char *argv[])
{
 
    int FNum;
// Check usage.
    if ( argc < 2 ) 
    {
        cerr << "Usage:\n\t" << argv[0] << " file_name" << endl;
        exit (-1);
    }
    for ( FNum = 1; FNum < argc; FNum++ )
    {
// Open an input file
        ifstream GraphData (argv[FNum]);
        if ( ! GraphData.good () ) 
        {
            cerr << "Could not open GraphData file\n";
            exit (-1);
        }
        cout << "\n\nOpened file " << argv[FNum] << " for processing\n";
        int GSize;
        GraphData >> GSize;
        if ( GraphData.bad () ) 
        {
            cerr << "Bad read\n";
            exit (-1);
        }
        Graph G(GSize); // Declare a graph.
// ...
}
 
class Graph
{
 
public:
 
Graph ( const int &);     // Constructor
void Print ();         // Print a rectangular adjacency matrix - not used
void PrintEdge ( const int &, const int & );     // Print one edge.        
Edge GetEdge ( const int &, const int & );     // Get an Edge object
void SetEdge ( const Edge & );             // Set an edge weight.
float GetWeight ( const int &, const int & ) ;  // Get an edge weight from
                        // the graph.
int GetSize ();                 // Return number of nodes
 
private:
 
int NumVert;             // Number of nodes.
float *AdjMat;             // Adjacency matrix.
 
};
 
// Parameter: GraphSize - number of nodes.
// Graph constructor. Create an empty
// adjacency matrix of size ( GraphSize ^2 ).
 
Graph::Graph ( const int &GraphSize )
{
 
// allocate memory for the adjacency matrix
    AdjMat = new float[GraphSize * GraphSize];
    NumVert = GraphSize;     // Initialize NumVert private member
    for ( int i=0; i < NumVert; i++ ) // Initalize all edges to ENOEDGE
       for ( int j=0; j < NumVert; j++ )
        AdjMat[(i * GraphSize) + j] = ENOEDGE;
}
 
 

thanks
regards,
usha

[weaknessforcats]

AdjMat = new float[GraphSize * GraphSize];
 

How big is this array?? One float is 4 bytes.

A bad_alloc exception is thrown by new when it runs out of heap memory.

[Ganon11]

Chenged the thread title.

[AdrianH]

Hi jyothiusha,

I apologise for erasing most of your code, but if you look at the posting guidelines, it states to post only relevant sections. If you are new to C++, this may be a little difficult, but here are some tips:

• When you compile, you will be given file names and line numbers where the errors/warnings occur. Post these along with the line where the problem occurred. Actually, don’t just post the one line, but with a bit of context. The amount of context could be up to the beginning of the function with supporting class(es).
  
• It is a good idea to break the problem down in to smaller pieces so that you can post something that is compliable, but contains only what is necessary to replicate the error that you are having. In fact, by doing this, you will be more than halfway there to figuring out what the problem is yourself.
  
• Keep your functions small to make debugging it easier. The less irrelevant information in the function the better. In fact, a function should contain no irrelevant information, as that adds to the noise, making your function harder to read and debug (what you have done is right on the money there ;)).
  
• If it becomes necessary for someone to ask you for the entire code base, please Private Message (PM) it to the party asking for it.

All of these points will actually help you in learning how to debug your code yourself.

Now as for your problem, weaknessforcats is probably correct. Check out what the value of GraphSize is when it is read in from the file. If you know that the file is correct and that you are parsing it correctly, you may be parsing it incorrectly. Print out the value you are reading in and that may give you an idea of what is going wrong.

Hope this helps, come back if you are still having trouble.


Adrian