这是个很简单的组件，编写它的目的也很单纯，就是想解决数据录入时的特殊字符检查问题。一开始要写函数实现，不过觉得麻烦，后来就想到写一个简单的VCL来遍历Form上所有的组件的方法。这个VCL目前只是检查所有的TEdit和TComboBox组件，有兴趣的朋友可以自己扩充功能。
我想这个VCL对于编写数据库程序的人员来说还是有一点帮助的，比如对单引号的Check。
想要检查什么符号只要在属性中设置一下就搞定，而且运行时只需要执行一个Checking函数，他就会自动检查咯。
它的另一个作用就是可以作为编写VCL的简单入门例程。
unit SymbolChecker;
interface
uses
Windows, Messages, SysUtils, Classes, Controls,StdCtrls,Dialogs,StrUtils;
type
TCheckControl = (cTEdit, cTComboBox);
TCheckControls = set of TCheckControl;
TSymbolChecker = class(TComponent)
private
{ Private declarations }
FActive: boolean;
FCheckControls:TCheckControls;
FCheckString:String;
procedure SetActive(Value: boolean);
procedure SetCheckControls(Value: TCheckControls);
procedure SetCheckString(Value: String);
protected
{ Protected declarations }
public
{ Public declarations }
constructor Create(AOwner: TComponent); override;
published
{ Published declarations }
procedure Checking();
property Active: boolean read FActive write SetActive default false;
property CheckControls: TCheckControls read FCheckControls write SetCheckControls default [cTEdit, cTComboBox];
property CheckString: String read FCheckString write SetCheckString;
end;
procedure Register;
implementation
procedure Register;
begin
RegisterComponents('MyVCL', [TSymbolChecker]);
end;
constructor TSymbolChecker.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
CheckControls := [cTEdit, cTComboBox];
end;
{ Set property Active Value }
procedure TSymbolChecker.SetActive(Value: boolean);
begin
if Value = FActive then exit;
FActive := Value;
end;
{ Set property CheckControls Value }
procedure TSymbolChecker.SetCheckControls(Value: TCheckControls);
begin
if Value = FCheckControls then exit;
FCheckControls := Value;
end;
{ Set property CheckString Value }
procedure TSymbolChecker.SetCheckString(Value: String);
begin
if Value = FCheckString then exit;
FCheckString := Value;
if Trim(FCheckString) = '' then SetActive(false);
end;
procedure TSymbolChecker.Checking();
var
I,J:integer;
begin
{ property Active=true then execute }
if FActive then
begin
{ property CheckTEdit=true then execute }
for I:= 0 to owner.ComponentCount - 1 do
begin
{ Check TEdit }
if (owner.Components[I] is TEdit) and (cTEdit in CheckControls) then
begin
for J :=1 to Length(Trim(FCheckString)) do
begin
if pos(MidStr(Trim(FCheckString),J,1),TEdit(owner.Components[I]).Text)>0 then
begin
ShowMessage('error symbol!');
TEdit(owner.Components[I]).SetFocus;
exit;
end;
end;
end;
{ Check TComboBox }
if (owner.Components[I] is TComboBox) and (cTComboBox in CheckControls) then
begin
for J :=1 to Length(Trim(FCheckString)) do
begin
if pos(MidStr(Trim(FCheckString),J,1),TComboBox(owner.Components[I]).Text)>0 then
begin
ShowMessage('error symbol!');
TComboBox(owner.Components[I]).SetFocus;
exit;
end;
end;
end;
end;
end;
end;
end.
最后要说明一点的是它是用Delphi6写的。
：） 
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