？在unit1里调unit2的，就要先把unit2的head file给include进来原码

[cyg1dm]

表单1
#include <vcl.h>
#pragma hdrstop

#include "Unit1.h"
#include "Unit2.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
: TForm(Owner)
{
}
//---------------------------------------------------------------------------

void __fastcall TForm1::Button1Click(TObject *Sender)
{
Unit2->ShowModal();
}
//---------------------------------------------------------------------------
表单2

#include <vcl.h>
#pragma hdrstop

#include "Unit2.h"
#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm2 *Form2;
//---------------------------------------------------------------------------
__fastcall TForm2::TForm2(TComponent* Owner)
: TForm(Owner)
{
}
//---------------------------------------------------------------------------

void __fastcall TForm2::FormCreate(TObject *Sender)
{

}
//---------------------------------------------------------------------------
出现错误：
[C++ Error] Unit1.cpp(21): E2451 Undefined symbol 'Unit2'

[xycleo]

Unit2->ShowModal();
这里错了！！

是Form2->ShowModal();

[rh]

哈哈~~给和尚分~~

[wjzhuang]

和尚，rh你们还在呀~~~~~~~~~
可惜我要下了，不然可以聊聊~~~~~

[Sephil]

和尚对！