防止用户误输入是软件开发的一项必不可少的工作，除才之外，还要为用户的使用提供最大方便。当然，我们可以利用或开发新的组件，以完成这些功能。但是，在团队开发中，每个成员都用自己认为不错的组件开发自己所承担的模块，会给软件的后期维护带来麻烦。交工的时候，项目负责人可不买你的帐。如果你用函数调用来完成这些功能，老盖也管不着。下面就是针对常用delphi组件的限制用户输入函数，但愿网友们能用的上。（一）TEdit、TDBEdit、TComboBox、TDBComboBox的输入分三种类型限制：（1）任意输入（2）整数输入（3）浮点数输入限制的项目如下：（1）整数输入只能输入数字0-9、+、-（2）浮点输入只能输入数字0-9、+、-、.（3）+和-只能有其一，并且只能出现在最前面（4）.只能有一个（5）限制小数位数函数如下：procedure MxFormatKeyPress(Text:string;SelStart,SelLength:integer;var Key:Char;EditType:integer;Digits:integer);beginif (Key=#27) or (Key=#8) or (EditType=1) then exit;if EditType=2 thenif not (Key in ['0'..'9','+','-'] ) then Key:=#0;if EditType=3 thenif not (Key in ['0'..'9','+','-','.'] ) then Key:=#0;//控制+-if (Key ='-') or (Key='+' ) then beginif ((Pos('-',Text) > 0) or (Pos('+',Text) > 0 )) and(SelLength=0 ) then Key:=#0;if SelStart > 0 then Key:=#0;end;//控制.if (Key = '.') and (EditType=3 ) then beginif (Pos('.',Text) > 0) and (not((SelStart=Pos('.',Text) ))) then Key:=#0;if SelStart=0 then Key:=#0;if (Digits>0) and (SelStart+SelLength0) and (EditType=3) thenif (pos('.',Text )>0 ) and (SelStart>=pos('.',Text)) thenif length(Text)-pos('.',Text )>=Digits then Key:=#0;end;

此函数在所限制组件的OnKeyPress事件中调用。Key即为OnKeyPress携带的Key:Char参数；EditType为限制的类型：1-任意输入；2-整数输入；3-浮点输入；Digits为浮点数输入时小数的位数，如果是零，则可输入任意位数。另外，此函数只适用于有Text、SelStart、SelLength等属性的TWinControl类的派生类。具体限制各组件的二级函数如下：

限制TEdit、TDBEdit：procedure MxFormatEditKeyPress(Edit:TCustomEdit;var Key:Char;EditType:integer;Digits:integer);beginMxFormatKeyPress(Edit.Text,Edit.SelStart,Edit.SelLength,Key,EditType,Digits);end;

限制TComboBox：procedure MxFormatComboKeyPress(Combo:TComboBox;var Key:Char;EditType:integer;Digits:integer);beginMxFormatKeyPress(Combo.Text,Combo.SelStart,Combo.SelLength,Key,EditType,Digits);end;

限制TDBComboBox：procedure MxFormatDBComboKeyPress(Combo:TDBComboBox;var Key:Char;EditType:integer;Digits:integer);beginMxFormatKeyPress(Combo.Text,Combo.SelStart,Combo.SelLength,Key,EditType,Digits);end;

调用示例：假如Form1上有一ComboBox1，让用户只输入浮点数，并且小数位数为两位。则可以在ComboBox1的OnKeyPress事件中调用上面的函数，代码如下：procedure TForm1.ComboBox1KeyPress(Sender: TObject; var Key: Char);beginMxFormatComboKeyPress(Combobox1,Key,3,0);end;

如果你的窗体上有多各TComboBox，并且限制类型一致，则不必每个TComboBox都书写代码，只需为其中一个编写事件处理代码，其它作连接即可。procedure TForm1.ComboBox1KeyPress(Sender: TObject; var Key: Char);beginMxFormatComboKeyPress(Sender as TComboBox,Key,3,0);end;其它组件调用方法同上。

（二）时间的输入限制类型：（1）时分（2）时分秒组件采用TMaskEdit，数据敏感采用TDBEdit。限制项目如下：（1）小时只能输入0-23（2）分钟不超过59（3）秒不超过59（4）用户只能全删，而不能只删某一位数据（5）箭头键可以更改时间需要在组件的OnKeyPress和OnKeyDown事件中分别书写代码。

procedure MxFormatTimeKeyPress(ctl:TCustomMaskEdit;TimeFormat:integer;var Key:Char;dts:TDataSource);varTextSave:string;EditingPos:integer;//1-h 2-m 3-si:integer;NumChars:set of Char;SelStartSave,SelLengthSave:integer;CharValid:boolean;beginNumChars:=['0'..'9'];if Key=^V then Key:=#0;if not (Key in NumChars ) then exit;TextSave:=ctl.Text;SelStartSave:=ctl.SelStart;SelLengthSave:=ctl.SelLength;case ctl.SelStart of0,1: EditingPos:=1;3,4: EditingPos:=2;6,7: EditingPos:=3;else EditingPos:=0;end;///////////////////////////////////////CharValid:=true;case EditingPos of1: beginif SelStartSave=0 then beginif not (Key in ['0'..'2']) then CharValid := False;if (Key ='2' ) and (TextSave[2] in ['4'..'9']) thenCharValid:=false;end;if (SelStartSave = 1) and (TextSave[1] = '2') and(not (Key in ['0'..'3'])) then CharValid := False;end;2: if (SelStartSave = 3) and not (Key in ['0'..'5']) then CharValid := False;3: if (SelStartSave = 6) and not (Key in ['0'..'5']) then CharValid := False;end;if not CharValid then beginKey:=#0;exit;end;if dts<>nil then dts.DataSet.Edit;if not (SelStartSave in [2,5]) then TextSave[SelStartSave+1]:=Key;if SelLengthSave>1 then beginfor i:=SelStartSave+2 to SelStartSave+SelLengthSave doif i in [1,2,4,5,7,8] then TextSave[i]:='0';SelLengthSave:=1;end;for i:=1 to length(TextSave) doif (i in [1,2,4,5,7,8]) and (not (TextSave[i] in NumChars ) ) thenTextSave[i]:='0';////////////////////////////////////if SelStartSave in [1,4] thenSelStartSave :=SelStartSave+2else if SelStartSave=length(TextSave)-1 thenSelStartSave :=SelStartSaveelse SelStartSave :=SelStartSave+1;/////////////////////////////////////ctl.Text :=TextSave;ctl.SelStart :=SelStartSave;ctl.SelLength :=SelLengthSave;Key:=#0;end;

//此函数分割时间，因为有时候会遇到非法的时间字符串，所以不采用DecodeTime。function MxSplitStr(SourceStr,SplitStr:string;var ResultArray:array of string):integer;vari:integer;strTmp:string;beginstrTmp:=SourceStr;i:=0;while pos(SplitStr,strTmp)>0 do beginResultArray[i]:=copy(strTmp,1,pos(SplitStr,strTmp)-1);strTmp:=copy(strTmp,pos(SplitStr,strTmp)+length(SplitStr),length(strTmp)-pos(SplitStr,strTmp));i:=i+1;end;ResultArray[i]:=strTmp;result:=i+1;end;//此函数检查字符串是否为合法的时间function TimeValid(TimeStr:string;TimeFormat:integer):boolean;varh,m,s:string;ary:array[0..2] of string;SplitRet:integer;i:integer;beginresult:=true;SplitRet:=MxSplitStr(TimeStr,':',ary);if SplitRet<2 then beginresult:=false; exit;end;for i:=0 to 2 do beginif length(ary[i])>2 then beginresult:=false; exit;end;ary[i]:=trim(ary[i]);end;h:=ary[0];m:=ary[1];if TimeFormat=3 then s:=ary[2];///////////////////////////////if (h='') or (strtoint(h)>23 ) then beginresult:=false; exit;end;if (m='' ) or (strtoint(m)>59) then beginresult:=false; exit;end;if (TimeFormat=3) thenif (s='') or (strtoint(s)>59) then beginresult:=false; exit;end;end;//此函数对时分秒进行加减运算function IncTime(ATime: TDateTime; Hours, Minutes, Seconds,MSecs: Integer): TDateTime;beginResult := ATime + (Hours div 24) + (((Hours mod 24) * 3600000 +Minutes * 60000 + Seconds * 1000 + MSecs) / MSecsPerDay);if Result < 0 then Result := Result + 1;end;//时分秒加减运算的二级函数function TimeAdd(TimeStr:string;TimeFormat:integer;HStep,MStep,SStep:integer):string;vardt:Tdatetime;beginif not TimeValid(TimeStr,TimeFormat) thenif TimeFormat=2 then begin result:='00:00'; exit; endelse begin result:='00:00:00';exit; end;dt:=strtotime(TimeStr);if TimeFormat=2 thenresult:=FormatDateTime('hh:mm',IncTime(dt,HStep,MStep,SStep,0))elseresult:=FormatDateTime('hh:mm:ss',IncTime(dt,HStep,MStep,SStep,0))end;//限制组件的OnKeyDownprocedure MxFormatTimeKeyDown(ctl:TCustomMaskEdit;TimeFormat:integer;var Key:word;Shift: TShiftState;dts:TDataSource);varTextSave:string;SelStartSave,SelLengthSave:integer;EditingPos:integer;//1-h 2-m 3-si:integer;beginif (ssShift in Shift) and (Key<>vk_delete ) then exit;if not (Key in [vk_delete,vk_back,vk_up,vk_down] ) then exit;if (dts<>nil ) and (not dts.DataSet.Active ) then exit;if (dts<>nil) and (not dts.DataSet.Modified ) thendts.DataSet.Edit;//////////////////////////////////////TextSave:=ctl.Text;SelStartSave:=ctl.SelStart;SelLengthSave:=ctl.SelLength;case SelStartSave of0,1: EditingPos:=1;3,4: EditingPos:=2;6,7: EditingPos:=3;else EditingPos:=0;end;if SelStartSave=length(TextSave) thenEditingPos:=TimeFormat;if Key=vk_delete then beginif SelLengthSave=length(TextSave) then TextSave:=''else beginif not (SelStartSave in [2,5]) then TextSave[SelStartSave+1]:='0';if SelLengthSave>1 then beginfor i:=SelStartSave+2 to SelStartSave+SelLengthSave doif i in [1,2,4,5,7,8] then TextSave[i]:='0';SelLengthSave:=1;end;end;Key:=0;end;if Key=vk_back then beginif SelLengthSave=length(TextSave) then TextSave:=''else if SelLengthSave<=1 then beginif not (SelStartSave in [3,6]) then beginTextSave[SelStartSave]:='0';SelStartSave:=SelStartSave-1;end else beginTextSave[SelStartSave-1]:='0';SelStartSave:=SelStartSave-2;end;SelLengthSave:=1;end else beginfor i:=SelStartSave+1 to SelStartSave+SelLengthSave doif i in [1,2,4,5,7,8] then TextSave[i]:='0';SelLengthSave:=1;end;Key:=0;end;///////////////////////////////////////if (Key=vk_up) or (Key=vk_down ) then beginif trim(TextSave)=':' then beginif TimeFormat=2 then TextSave:='00:00'else TextSave:='00:00:00'end else beginif Key=vk_up thencase EditingPos of1: TextSave:=TimeAdd(TextSave,TimeFormat,1,0,0);2: TextSave:=TimeAdd(TextSave,TimeFormat,0,1,0);3: TextSave:=TimeAdd(TextSave,TimeFormat,0,0,1);end;if Key=vk_down thencase EditingPos of1: TextSave:=TimeAdd(TextSave,TimeFormat,-1,0,0);2: TextSave:=TimeAdd(TextSave,TimeFormat,0,-1,0);3: TextSave:=TimeAdd(TextSave,TimeFormat,0,0,-1);end;end;end;///////////////////////////////////////ctl.Text :=TextSave;ctl.SelStart :=SelStartSave;ctl.SelLength :=SelLengthSave;end;以上函数的TimeFormat参数代表时间的类型：1-时:分；2-时:分:秒要完成对时间的输入限制，只需调用上面的MxFormatTimeKeyPress，MxFormatTimeKeyDown两个函数。调用示例：（1）TMaskEditprocedure TForm1.MaskEdit1KeyDown(Sender: TObject; var Key: Word;Shift: TShiftState);beginMxFormatTimeKeyDown(Sender as TCustomMaskEdit,2,Key,Shift,nil);end;

procedure TForm1.MaskEdit1KeyPress(Sender: TObject; var Key: Char);beginMxFormatTimeKeyPress(Sender as TCustomMaskEdit,2,Key,nil);end;并且，TMaskEdit的EditMask属性设为'99:99'（2）TDBEdit

procedure TForm1.DBEdit1KeyPress(Sender: TObject; var Key: Char);beginMxFormatTimeKeyPress(Sender as TCustomMaskEdit,2,Key,(Sender as TDBEdit).DataSource);end;

procedure TForm1.DBEdit1KeyDown(Sender: TObject; var Key: Word;Shift: TShiftState);beginMxFormatTimeKeyDown(Sender as TCustomMaskEdit,2,Key,Shift,(Sender as TDBEdit).DataSource);end;在TDBEdit所连接的数据源打开后，设定所连字段的EditMask属性为99:99：DBEdit1.Field.EditMask :='99:99';

（三）日期的输入采用Rx的日期组件TDateEdit、TDBDateEdit。如果你还没安装，请在本站下载。无需对日期的输入作限制，只需方便用户的输入。即：箭头键可以改变相应的日期元素，因为Rx五次功能。函数如下：procedure MxSpinRxDateEdit(Edit:TCustomDateEdit;Key:word;Shift:TShiftState;dts:TDataSource);varDateStr,Mark,str:string;MarkPos1,MarkPos2:integer;DateOrd:TDateOrder;DateFlag,step:integer;OldSelStart:integer;beginif Shift<>[] then exit;if not (Key in [vk_up,vk_down] ) then exit;if (dts<>nil ) and (not dts.DataSet.Active ) then exit;if (dts<>nil ) and (not dts.DataSet.Modified) thendts.DataSet.Edit;OldSelStart:=Edit.SelStart;DateStr:=Edit.EditText;Mark:=GetDateMark(DateStr);MarkPos1:=pos(Mark,DateStr);str:=copy(DateStr,MarkPos1+1,length(DateStr)-MarkPos1);MarkPos2:=MarkPos1+pos(Mark,str);DateOrd:=GetDateOrder(ShortDateFormat);DateFlag:=GetDateFlag(MarkPos1,MarkPos2,Edit.SelStart,DateOrd);if Key=vk_up then step:=1else if Key=vk_down then step:=-1else step:=0;case DateFlag of1: Edit.Date := IncYear(Edit.Date ,step);2: Edit.Date := IncMonth(Edit.Date ,step);3: Edit.Date := IncDay(Edit.Date ,step);end;Edit.SelStart :=OldSelStart;end;

此函数在组件的OnKeyDown事件中调用，对于TDateEdit，DataSoure参数为nil。记着引用Rx的单元ToolEdit和DateUtil。调用示例：procedure TForm1.DateEdit1KeyDown(Sender: TObject; var Key: Word;Shift: TShiftState);beginMxSpinRxDateEdit(Sender as TCustomDateEdit,Key,Shift,nil);end;

procedure TForm1.DBDateEdit1KeyDown(Sender: TObject; var Key: Word;Shift: TShiftState);beginMxSpinRxDateEdit(Sender as TCustomDateEdit,Key,Shift,(Sender as TDBDateEdit).DataSource);end;

Technorati : delphi, 限制输入