Exception in cmdtarg.cpp

Hi
I had exception on the following line in cmdtarg.cpp while trying to implement a code:

"case AfxSigCmd_v:
// normal command or control notification
ASSERT(CN_COMMAND == 0); // CN_COMMAND same as BN_CLICKED
ASSERT(pExtra == NULL);
(pTarget->*mmf.pfnCmd_v_v)();
break; "
On the break line.

This is the code I put in:

double x=0,y=0,z=0;
TopoDS_Vertex V3;
string delim(" ");
fstream is;
string buffer;
double value(0.);
int dimCount(0);
string row;
stringstream newRow;

is.open ("points.txt");
if (!is)
{
cerr exit(1);
}
//ofstream out(tempfile.c_str());

getline(is, row);
if (row == "")
{
//cout getchar();
}
//cout string::size_type lastPos = row.find_first_not_of(delim, 0);
string::size_type pos = row.find_first_of(delim, lastPos);
while (string::npos != pos || string::npos != lastPos)
{
dimCount++;
buffer = row.substr(lastPos, pos - lastPos);

value = atof(buffer.c_str());
//cout lastPos = row.find_first_not_of(delim, pos);
pos = row.find_first_of(delim, lastPos);
if (dimCount == 1)
{
x = value;
}
else if (dimCount == 2)
{
y = value;
}
else if (dimCount == 3)
{
z = value;
}
else
{
cerr }
}
dimCount = 0;

gp_Pnt P(x,y,z);
BRepBuilderAPI_MakeVertex MV(P);
V3 = MV.Vertex();

Handle(AIS_Shape) Point3 = new AIS_Shape(V3);
myAISContext->Display(Point3,Standard_False);

Please provide any suggestions on the problem.
Thanks.

Nitin