运行时出现的有关问题!待,多谢!

运行时出现的问题!在线等待,谢谢!!
--Line.h----------------
#include   <fstream>
using       namespace       std;  

struct   TYPE_DXF
{
float   x1,x2,y1,y2;
};

class   Line
{
public:
Line(char*   filepath,   TYPE_DXF   coordinate);
~Line();
void   Write();
protected:
TYPE_DXF   dxf;
ofstream   stream;
};


-----Line.cpp-------
#include   "Link.h "
Line::Line(char*   filepath,   TYPE_DXF   coordinate)
{
dxf.x1   =   coordinate.x1;
dxf.x2   =   coordinate.x2;
dxf.y1   =   coordinate.y1;
dxf.y2   =   coordinate.y2;

        stream.open(filepath);
if(stream.fail())
{
cout   < <   "error   opening   file   "   < <   filepath   < <endl;
exit(0);
}
}

Line::~Line()
{
delete   stream;
}

void   Line::Write()
{
stream   < <   "0\n "
< <   "SECTION\n "
< <   "2\n "
< <   "ENTITIES\n "
< <   "0\n "
< <   "LINE\n "
< <   "8\n "
< <   "LINE\n "
< <   "10\n "
< <   dxf.x1   < <   "\n "
< <   "11\n "
< <   dxf.x2   < <   "\n "
< <   "20\n "
< <   dxf.y1   < <   "\n "
< <   "21\n "  
< <   dxf.y2   < <   "\n "
< <   "0\n "
< <   "ENDSEC\n "
< <   "0\n "
< <   "EOF "
< <   endl;
}

---------DrawLine.cpp--------
#include   <iostream.h>
#include   "Line.h "

void   main()
{
char   filepath[100];
TYPE_DXF   coordinate;

cout   < < "请输入直线的相关数据：\n "
< < "x1: "
< <endl;
cin   > >   coordinate.x1;
cout   < < "y1: ";
cin   > >   coordinate.y1;
cout   < <   "x2 ";
cin   > >   coordinate.x2;
cout   < <   "y2 ";
cin   > >   coordinate.y2;

cout   < <   "输入所要保存的文件名(dxf类型): ";
cin   > >   filepath;

Line   line(filepath,   coordinate);
line.Write();
}
不知道为什么在编译连接时都没错，就是在运行时出现错误

Debug   Assertion   Failed!

Program:F:\a\Debug\DrawLine.exe
File:dbgheap.c
Line:1044

Expression:   _CrtIsValidHeapPointer(pUserData)

For   information   on   how   your   program   can   cause   an   assertion   failure,   see   the   Visual   C++   documentation   on   asserts.
(Press   Retry   to   debug   the   application)

终止A     重试R     忽略I

这个是什么原因

------解决方案--------------------

/*********** line.h ************/
#include <fstream>
using namespace std;

struct TYPE_DXF
{
float x1,x2,y1,y2;
};

class Line
{
public:
Line(char* filepath, TYPE_DXF coordinate);
~Line();
void Write();
protected:
TYPE_DXF dxf;
ofstream stream;
};

/*********** line.cpp ************/
#include <iostream>
#include "line.h "
using namespace std;

Line::Line(char* filepath, TYPE_DXF coordinate)
{
dxf.x1 = coordinate.x1;
dxf.x2 = coordinate.x2;
dxf.y1 = coordinate.y1;
dxf.y2 = coordinate.y2;

stream.open(filepath);
if(stream.fail())
{
cout < < "error opening file " < < filepath < <endl;
exit(0);
}
}

Line::~Line()
{
delete stream;
}

void Line::Write()
{
stream < < "0\n "
< < "SECTION\n "
< < "2\n "
< < "ENTITIES\n "
< < "0\n "
< < "LINE\n "
< < "8\n "
< < "LINE\n "
< < "10\n "
< < dxf.x1 < < "\n "
< < "11\n "
< < dxf.x2 < < "\n "
< < "20\n "
< < dxf.y1 < < "\n "
< < "21\n "
< < dxf.y2 < < "\n "
< < "0\n "
< < "ENDSEC\n "
< < "0\n "
< < "EOF "
< < endl;
}

/*********** DrawLine.cpp ************/
#include <iostream.h>
#include "Line.h "

int main()
{
char filepath[100];
TYPE_DXF coordinate;

cout < < "&Ccedil;&euml;&Ecirc;&auml;&Egrave;&euml;&Ouml;±&Iuml;&szlig;&micro;&Auml;&Iuml;à&sup1;&Oslash;&Ecirc;&yacute;&frac34;&Yacute;&pound;&ordm;\n "
< < "x1: "
< <endl;
cin > > coordinate.x1;
cout < < "y1: ";
cin > > coordinate.y1;
cout < < "x2 ";
cin > > coordinate.x2;
cout < < "y2 ";
cin > > coordinate.y2;

cout < < "&Ecirc;&auml;&Egrave;&euml;&Euml;ù&Ograve;&ordf;±&pound;&acute;&aelig;&micro;&Auml;&Icirc;&Auml;&frac14;&thorn;&Atilde;&ucirc;(dxf&Agrave;à&ETH;&Iacute;): ";
cin > > filepath;

Line line(filepath, coordinate);
line.Write();

return 0;
}

已经编译连接通过，可以正常运行了。