代码报错 ：[C++ Error] Unit1.cpp(23): E2451 Undefined symbol 'ValidFile'

Question

//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop

#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
: TForm(Owner)
{

}
//---------------------------------------------------------------------------
void __fastcall TForm1::ButOpenClick(TObject *Sender)
{
if(OpenDialog1->Execute())
{
LoadFile->Text = OpenDialog1->FileName;
ValidFile = true;
}
else
{
LoadFile->Text="";
ValidFile = false;

}

}
//---------------------------------------------------------------------------
void __fastcall TForm1::ButSendClick(TObject *Sender)
{
if(!ValidFile) //核实载入的文件
{
MessageBox(NULL,"没有选择需要发送的文件","错误",MB_ICONERROR);
return;
}
NMStrm1->Host = Host->Text;
NMStrm1->ReportLevel = Status_Basic;
TFileStream *Strm = new TFileStream(LoadFile->Text,fmOpenRead);
NMStrm1->PostIt(Strm);
delete Strm; //删除变量
}
//---------------------------------------------------------------------------
void __fastcall TForm1::NMStrmServ1MSG(TComponent *Sender,
const AnsiString sFrom, TStream *strm)
{
char *Buffer = new char[strm->Size+1];
strm->ReadBuffer(Buffer,strm->Size);
RichEdit1->Lines->Text = Buffer;
delete[]Buffer; //删除缓冲区

}
//---------------------------------------------------------------------------
void __fastcall TForm1::NMStrm1Connect(TObject *Sender)
{
StatusBar1->SimpleText = "连接成功";
}
//---------------------------------------------------------------------------
void __fastcall TForm1::NMStrm1MessageSent(TObject *Sender)
{
StatusBar1->SimpleText = "数据发送成功";
}
//---------------------------------------------------------------------------
void __fastcall TForm1::NMStrm1HostResolved(TComponent *Sender)
{
StatusBar1->SimpleText = "主机解析成功";
}
//---------------------------------------------------------------------------
这是报的错：：[C++ Error] Unit1.cpp(23): E2451 Undefined symbol 'ValidFile'
[C++ Error] Unit1.cpp(36): E2451 Undefined symbol 'ValidFile'
能不能告诉我所有类似问题的解决方法！！

Answer 1

没有定义变量ValidFile，或者你在其他头文件里定义了，但是没有包含头文件

Answer 2

ValidFile 没有定义，
在前面加个 bool ValidFile