我現在自訂一個Image要讓它能夠利用左右鍵移動
可是現在出現問題[C Error] Unit1.cpp(70): E2451 Undefined symbol 'La'
問過朋友也找不出原因
請問是哪裡出問題 要如何改寫
[code cpp]
//---------------------------------------------------------------------------

#include
#pragma hdrstop

#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;

class Launcher
{
private:
TImage *La;

public:
Launcher();
~Launcher();
int GetLeft(),GetWidth();
};
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
: TForm(Owner)
{
}
//---------------------------------------------------------------------------
Launcher::Launcher()
{
La=new TImage(Form1);
La->Parent=Form1;
La->Picture->LoadFromFile("2.bmp");
La->Width=La->Picture->Width;
La->Height=La->Picture->Height;
La->Left=Form1->ClientWidth/2;
La->Top=Form1->ClientHeight-La->Height;
}
Launcher::~Launcher(){
La->Visible=false;
delete La;
}
int Launcher::GetLeft()
{
return La->Left;
}


int Launcher::GetWidth()
{
return La->Width;
}
void __fastcall TForm1::FormCreate(TObject *Sender)
{
new Launcher();
Panel1->Height=Form1->ClientHeight;
Panel1->Top=0;
Panel1->Left=Form1->ClientWidth-Panel1->Width;
}
//---------------------------------------------------------------------------


void __fastcall TForm1::FormKeyDown(TObject *Sender, WORD &Key,
TShiftState Shift)
{
if( Key == VK_RIGHT ) // Right arrow
{
La->GetLeft() = La->GetLeft() 20;
// if( Image1->Left Image1->Width >= Form1->ClientWidth)
// Image1->Left = Form1->ClientWidth-Image1->Width 0;
if( La->GetLeft() La->GetWidth() >= Form1->ClientWidth-Panel1->Width)
La->GetLeft() = Form1->ClientWidth-Panel1->Width-La->GetWidth();


}
else if( Key == VK_LEFT ) // Left arrow key
{
La->GetLeft() = La->GetLeft() - 20;
if( La->GetLeft() <= 0 )
La->GetLeft()= 0;
}
}
//---------------------------------------------------------------------------


[/code]

編輯記錄

你用副程式這樣好像有點多此一舉
而且語法有點怪 有可能是我程度不夠請見量
ex:
if( Key ==39 ) // Right arrow
Image1->Left =20; //Image1是我的圖片
這樣應該簡化很多


===================引 用 ji3g4go61125 文 章===================
我現在自訂一個Image要讓它能夠利用左右鍵移動
可是現在出現問題[C Error] Unit1.cpp(70): E2451 Undefined symbol 'La'
問過朋友也找不出原因
請問是哪裡出問題 要如何改寫
[code cpp]
//---------------------------------------------------------------------------

#include
#pragma hdrstop

#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;

class Launcher
{
private:
TImage *La;

public:
Launcher();
~Launcher();
int GetLeft(),GetWidth();
};
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
: TForm(Owner)
{
}
//---------------------------------------------------------------------------
Launcher::Launcher()
{
La=new TImage(Form1);
La->Parent=Form1;
La->Picture->LoadFromFile("2.bmp");
La->Width=La->Picture->Width;
La->Height=La->Picture->Height;
La->Left=Form1->ClientWidth/2;
La->Top=Form1->ClientHeight-La->Height;
}
Launcher::~Launcher(){
La->Visible=false;
delete La;
}
int Launcher::GetLeft()
{
return La->Left;
}


int Launcher::GetWidth()
{
return La->Width;
}
void __fastcall TForm1::FormCreate(TObject *Sender)
{
new Launcher();
Panel1->Height=Form1->ClientHeight;
Panel1->Top=0;
Panel1->Left=Form1->ClientWidth-Panel1->Width;
}
//---------------------------------------------------------------------------


void __fastcall TForm1::FormKeyDown(TObject *Sender, WORD &Key,
TShiftState Shift)
{
if( Key == VK_RIGHT ) // Right arrow
{
La->GetLeft() = La->GetLeft() 20;
// if( Image1->Left Image1->Width >= Form1->ClientWidth)
// Image1->Left = Form1->ClientWidth-Image1->Width 0;
if( La->GetLeft() La->GetWidth() >= Form1->ClientWidth-Panel1->Width)
La->GetLeft() = Form1->ClientWidth-Panel1->Width-La->GetWidth();


}
else if( Key == VK_LEFT ) // Left arrow key
{
La->GetLeft() = La->GetLeft() - 20;
if( La->GetLeft() <= 0 )
La->GetLeft()= 0;
}
}
//---------------------------------------------------------------------------


[/code]

------
有問題大家多討論
大家共同一起進步

編輯記錄

這是作業要求使用類別
所以才這樣用
不過這支程式還沒完成
只是想先看它會不會動

可是現在出現問題[C Error] Unit1.cpp(70): E2451 Undefined symbol 'La'
是不是因為private:(私有型態) TImage *La; 就無法給TForm1用阿
程度不夠請見諒....BCB初學者

===================引 用 ji3g4go61125 文 章===================
我現在自訂一個Image要讓它能夠利用左右鍵移動
可是現在出現問題[C Error] Unit1.cpp(70): E2451 Undefined symbol 'La'
問過朋友也找不出原因
請問是哪裡出問題 要如何改寫
[code cpp]
//---------------------------------------------------------------------------

#include
#pragma hdrstop

#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;

class Launcher
{
private:
TImage *La;

public:
Launcher();
~Launcher();
int GetLeft(),GetWidth();
};
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
: TForm(Owner)
{
}
//---------------------------------------------------------------------------
Launcher::Launcher()
{
La=new TImage(Form1);
La->Parent=Form1;
La->Picture->LoadFromFile("2.bmp");
La->Width=La->Picture->Width;
La->Height=La->Picture->Height;
La->Left=Form1->ClientWidth/2;
La->Top=Form1->ClientHeight-La->Height;
}
Launcher::~Launcher(){
La->Visible=false;
delete La;
}
int Launcher::GetLeft()
{
return La->Left;
}


int Launcher::GetWidth()
{
return La->Width;
}
void __fastcall TForm1::FormCreate(TObject *Sender)
{
new Launcher();
Panel1->Height=Form1->ClientHeight;
Panel1->Top=0;
Panel1->Left=Form1->ClientWidth-Panel1->Width;
}
//---------------------------------------------------------------------------


void __fastcall TForm1::FormKeyDown(TObject *Sender, WORD &Key,
TShiftState Shift)
{
if( Key == VK_RIGHT ) // Right arrow
{
La->GetLeft() = La->GetLeft() 20;
// if( Image1->Left Image1->Width >= Form1->ClientWidth)
// Image1->Left = Form1->ClientWidth-Image1->Width 0;
if( La->GetLeft() La->GetWidth() >= Form1->ClientWidth-Panel1->Width)
La->GetLeft() = Form1->ClientWidth-Panel1->Width-La->GetWidth();


}
else if( Key == VK_LEFT ) // Left arrow key
{
La->GetLeft() = La->GetLeft() - 20;
if( La->GetLeft() <= 0 )
La->GetLeft()= 0;
}
}
//---------------------------------------------------------------------------


[/code]

1.你沒宣告要給誰用
Launcher *myobj; //在全域宣告
myobj = new Launcher(); //在FormCreate
delete myobj; //用完就要delete,在FormClose

2.Launcher的La是private，其他類別(如Form)不能直接叫用它
你寫的GetLeft()和GetWidth()這兩個function不能那樣用，這只能取值，不能把值設進去
int tmp_left = myobj->GetLeft();
int tmp_width = myobj->GetWidth();
要麻用property的方式寫，
不然就把TImage *La;改public，然後直接用myobj->La->Left=20;

3.屬性property應該這樣寫
protected:
int getLaLeft() {return La->Left;};
void setLaLeft(int newLeft) {La->Left=newLeft;};
int getLaWidth() {return La->Width;};
void setLaWidth(int newWidth) {La->Width=newWidth;};
public:
__property int LaLeft ={write=setLaLeft ,read=getLaLeft };
__property int LaWidth={write=setLaWidth,read=getLaWidth};
然後這樣用
void __fastcall TForm1::FormKeyDown(TObject *Sender, WORD &Key,
TShiftState Shift)
{
if( Key == VK_RIGHT ) // Right arrow
{
myobj->LaLeft = 20;
}
}

you must use Launcher point new an Launcher before form1 member functinn use La


you can try Launcher *text = new Launcher;


but La is private for Launcher , so throuh text then form1 member functinn can be use

------
恩...

編輯記錄

提問者您好:


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