I am implementing a Graph ADT to use for a different program, and I was given these "insert" and "remove" functions that I needed to define. They are supposed to create an Edge (from the Edge struct) with two vertices and insert/remove it into a larger Graph. It runs fine when I create an instance of it in main, but when I try to call the insert or remove function it gives an error that says:
"First-chance exception at 0x00A56C84 in COMP222 -- Program3.exe: 0xC0000005: Access violation writing location 0xCDCDCDCD".
Any ideas as to what I could be doing wrong here to cause this error? Again, the main problem is with insert/remove, but I posted the rest of it just in case.
EDGE STRUCT
struct Edge { //edge with vertices v1 and v2
int *vertex1;
int *vertex2;
};
GRAPH.H
#include "Graph.h"
#include <iostream>
Graph::Graph() {
graphSize = 0;
};
Graph::Graph(const string& file) {
text.open(file);
while(!text.eof()) {
char ch;
text.get(ch);
vertices.push_back(ch);
}
for(int i = 0;i < sizeof(vertices);i++) {
static_cast<int>(vertices.at(i));
}
}
void Graph::insert(int v1,int v2) {
Edge* newEdge = new Edge;
*newEdge->vertex1 = v1;
*newEdge->vertex2 = v2;
v1 = vertices.at(0);
v2 = vertices.at(2);
graphSize += 2;
};
void Graph::remove(int v1,int v2) {
Edge* delEdge = new Edge; //edge to be deleted
*delEdge->vertex1 = v1;
*delEdge->vertex2 = v2;
delete delEdge->vertex1;
delete delEdge->vertex2;
graphSize -= 2;
};
ostream& operator <<(ostream& verts,const Graph& graph) {
return verts;
};
MAIN FUNCTION -- problem seems to be with the test.insert and test.remove functions
#include "Graph.h"
#include <iostream>
#include <string>
#include <fstream>
using namespace std;
int main() {
Graph test("Path to file...no problem here..."); //THIS WORKS FINE
test.insert(2,3); //INSERT/REMOVE CAUSE THE ERROR
test.remove(2,3);
system("PAUSE");
return 0;
}
The problem should with these two lines in the insert function:
*newEdge->vertex1 = v1;
*newEdge->vertex2 = v2;
vertex1
and vertex2
are uninitialized pointers, they are not pointing to valid locations in the memory and you are trying to write to those locations. I suspect you want vertex1
and vertex2
to simply be ints that hold vertex IDs.
A similarly write is attempted by your remove function. You should fix that too.
User contributions licensed under CC BY-SA 3.0