abs(x) 绝对值
arctan(x) 反正切
cos(x) 传回馀弦函数值
exp(x) e的x次幂
frac(x) 取小数部分
int(x) 取整
ln(x) 自然对数
sin(x) 传回正弦函数值
sqr(x) x*x
sqrt(x) 平方根
其它
pred(x) pred('D')='C', pred(true)=1;
succ(x) succ('Y')='Z', succ(pred(x))=x
ord(x) 求x在字符集中的序号,如ord('A')=65
chr(x) chr(65)='A'
round(x) 四舍五入
trunc(x) trunc(4.8)=4,trunc('-3.6')=-3
upcase(x) upcase('a')='A'
hi(I) hi($2A30)=$2A
lo(I) lo($2A30)=$30
random(n) 产生[0,n)间的随机整数
sizeof(name) 求出某类型或变量在内存中占用的字节数
swap(num) swap($3621)=$2136
================================
Arithmetic routines 数学运算
================================
Abs 绝对值
---------------------------------------------------------
Unit System
函数原型 function Abs(X);
说明 X为整数or实数.
范例
var
r: Real;
i: Integer;
begin
r := Abs(-2.3); { 2.3 }
i := Abs(-157); { 157 }
end;
----------------------------------------------------------
ArcTan 三角函数
----------------------------------------------------------
范例
Cos
var R: Extended;
begin
R := Cos(Pi);
end;
----------------------------------------------------------
Sin
----------------------------------------------------------
范例
var
R: Extended;
S: string;
begin
R := Sin(Pi);
Str(R:5:3, S);
Canvas.TextOut(10, 10, 'The Sin of Pi is ' + S);
end;
----------------------------------------------------------
Unit System
函数原型 function ArcTan(X: Extended): Extended;
函数原型 function Cos(X: Extended): Extended;
函数原型 function Sin(X: Extended): Extended;
----------------------------------------------------------
说明 X为径度.
Tan(x) === Sin(x) / Cos(x)
ArcSin(x) = ArcTan (x/sqrt (1-sqr (x)))
ArcCos(x) = ArcTan (sqrt (1-sqr (x)) /x)
左边这三个不是函数,而是右边运算求得.
范例
var
R: Extended;
begin
R := ArcTan(Pi);
end;
范例 var
R: Extended;
S: string;
begin
R := Sin(Pi);
Str(R:5:3, S);
Canvas.TextOut(10, 10, 'The Sin of Pi is ' + S);
end;
----------------------------------------------------------
Frac 求一个实数的小数部份
----------------------------------------------------------
Unit System
函数原型 function Frac(X: Real): Real;
说明 X为实数.
范例 var
R: Real;
begin
R := Frac(123.456); { 0.456 }
R := Frac(-123.456); { -0.456 }
end;
------------------------------------------
Int 求一个实数的整数部份
------------------------------------------
Unit System
函数原型 function Int(X: Real): Real;
说明 X为实数.
范例 var
R: Real;
begin
R := Int(123.456); { 123.0 }
R := Int(-123.456); { -123.0 }
end;
------------------------------------------
Pi 就是数学的Pi
------------------------------------------
Unit System
函数原型 function Pi: Extended;
说明 它是一个函数,但我们就把它当作是预设的变数来用吧!
Pi= 3.1415926535897932385
------------------------------------------
Sqr X的平方
-----------------------------------------
范例
var
S, Temp: string;
begin
Str(Sqr(5.0):3:1, Temp);
S := '5 squared is ' + Temp + #13#10;
Str(Sqrt(2.0):5:4, Temp);
S := S + 'The square root of 2 is ' + Temp;
MessageDlg(S, mtInformation, [mbOk], 0);
end;
-----------------------------------------
Sqrt X的平方根
------------------------------------------
Unit System
函数原型 function Sqr(X: Extended): Extended;
函数原型 function Sqrt(X: Extended): Extended;
范例 var
S, Temp: string;
begin
Str(Sqr(5.0):3:1, Temp);
S := '5 squared is ' + Temp + #13#10;
Str(Sqrt(2.0):5:4, Temp);
S := S + 'The square root of 2 is ' + Temp;
MessageDlg(S, mtInformation, [mbOk], 0);
end;
------------------------------------------
Ln 自然对数
------------------------------------------
范例
var
e : real;
S : string;
begin
e := Exp(1.0);
Str(ln(e):3:2, S);
S := 'e = ' + FloatToStr(e) + '; ln(e) = ' + S;
Canvas.TextOut(10, 10, S);
end;
----------------------------------------
Exp 指数
------------------------------------------
Unit System
函数原型 function Ln(X: Real): Real;
函数原型 function Exp(X: Real): Real;
范例 var
e : real;
S : string;
begin
e := Exp(1.0);
Str(ln(e):3:2, S);
S := 'ln(e) = ' + S;
Canvas.TextOut(10, 10, S);
end;
------------------------------------------
Date and time routines 日期及时间函数
------------------------------------------
Date 传回目前的日期
Unit SysUtils
函数原型 function Date: TDateTime;
范例 procedure TForm1.Button1Click(Sender: TObject);
begin
Label1.Caption := 'Today is ' + DateToStr(Date);
end;
------------------------------------------
DateTimeToStr 日期时间转换成内定型字串(1996/12/20 09:12:20 PM)
------------------------------------------
Unit SysUtils
函数原型 function DateTimeToStr(DateTime: TDateTime): string;
范例 procedure TForm1.Button1Click(Sender: TObject);
begin
Label1.Caption := DateTimeToStr(Now);
end;
--------------------------------------------------------
DateTimeToString 日期时间转换成自定型字串
-------------------------------------------------------
Unit SysUtils
函数原型 procedure DateTimeToString(var Result: string; const Format:
string; DateTime: TDateTime);
范例 procedure TForm1.FormCreate(Sender: TObject);
var
s:string;
begin
DateTimeToString(s,'dddd,mmmm d,yyyy "at" hh:mm
AM/PM',Now);
Label1.Caption :=s;
end;
结果 星期五,十二月 20,1996 at 09:20 PM
-----------------------------------------------------------------------------
**** Format格式叁考下面.FormatDateTime.
--------------------------------------------------------
DateToStr 日期转换成内定型字串.(1996/12/20)
--------------------------------------------------------
Unit SysUtils
函数原型 function DateToStr(Date: TDateTime): string;
范例
procedure TForm1.Button1Click(Sender: TObject);
begin
Label1.Caption := 'Today is ' + DateToStr(Date);
end;
# Date, DateToStr Example
--------------------------------------------------------
DayOfWeek 求叁数日期是星期几.
--------------------------------------------------------
Unit SysUtils
函数原型 function DayOfWeek(Date: TDateTime): Integer;
说明 传回值是一整数,1~7.
星期日为1.
范例
procedure TForm1.Button1Click(Sender: TObject);
var
ADate: TDateTime;
days: array[1..7] of string;
begin
days[1] := 'Sunday';
days[2] := 'Monday';
days[3] := 'Tuesday';
days[4] := 'Wednesday';
days[5] := 'Thursday';
days[6] := 'Friday';
days[7] := 'Saturday';
ADate := StrToDate(Edit1.Text);
ShowMessage(Edit1.Text + ' is a ' + days[DayOfWeek(ADate)];
end;
# StrToDate, DayOfWeek Example
--------------------------------------------------------
DecodeDate 将TDateTime型态的日期变数，转为Word型态.
--------------------------------------------------------
范例
procedure TForm1.Button1Click(Sender: TObject);
var
Present: TDateTime;
Year, Month, Day, Hour, Min, Sec, MSec: Word;
begin
Present:= Now;
DecodeDate(Present, Year, Month, Day);
Label1.Caption := 'Today is Day ' + IntToStr(Day) + ' of Month '
+ IntToStr(Month) + ' of Year ' + IntToStr(Year);
DecodeTime(Present, Hour, Min, Sec, MSec);
Label2.Caption := 'The time is Minute ' + IntToStr(Min) + ' of Hour '
+ IntToStr(Hour);
end;
# DecodeDate, DecodeTime Example
--------------------------------------------------------
DecodeTime 将TDateTime型态的时间变数，转为Word型态.
--------------------------------------------------------
Unit SysUtils
函数原型 procedure DecodeDate(Date: TDateTime; var Year, Month,Day: Word);
函数原型 procedure DecodeTime(Time: TDateTime; var Hour, Min, Sec,MSec: Word);
范例 procedure TForm1.Button1Click(Sender: TObject);
var
Present: TDateTime;
Year, Month, Day, Hour, Min, Sec, MSec: Word;
begin
Present:= Now;
DecodeDate(Present, Year, Month, Day);
Label1.Caption := 'Today is Day ' + IntToStr(Day) + ' of
Month ' + IntToStr(Month) + ' of Year ' + IntToStr(Year);
DecodeTime(Present, Hour, Min, Sec, MSec);
Label2.Caption := 'The time is Minute ' +IntToStr(Min) + ' of
Hour ' + IntToStr(Hour);
end;
--------------------------------------------------------
EncodeDate 将Word型态的日期变数，转为TDateTime型态.
--------------------------------------------------------
范例
procedure TForm1.Button1Click(Sender: TObject);
var
MyDate: TDateTime;
begin
MyDate := EncodeDate(StrToInt(Edit1.Text), StrToInt(Edit2.Text), StrToInt(Edit3.Text));
Label1.Caption := DateToStr(MyDate);
end;
-------------------------------------------------------
EncodeTime 将Word型态的时间变数，转为TDateTime型态.
--------------------------------------------------------
Unit SysUtils
函数原型 function EncodeDate(Year, Month, Day: Word): TDateTime;
函数原型 function EncodeTime(Hour, Min, Sec, MSec: Word):
TDateTime;
范例 procedure TForm1.Button1Click(Sender: TObject);
var
MyDate: TDateTime;
MyTime: TDateTime;
begin
MyDate := EncodeDate(83, 12, 31);
Label1.Caption := DateToStr(MyDate);
MyTime := EncodeTime(0, 45, 45, 7);
Label2.Caption := TimeToStr(MyTime);
end;
范例
procedure TForm1.Button1Click(Sender: TObject);
var
MyTime: TDateTime;
begin
MyTime := EncodeTime(0, 45, 45, 7);
Label1.Caption := TimeToStr(MyTime);
end;
--------------------------------------------------------
FormatDateTime 将日期时间依Format的格式转换给一字串.
--------------------------------------------------------
Unit SysUtils
函数原型 function FormatDateTime(const Format: string; DateTime:
TDateTime): string;
**** 类似DateTimeToString.
Format格式
c 内定值ShortDateFormat的格式.(1996/12/20 09:20:15 PM).
d 日期,前面不补0.(1-31)
dd 日期,前面补0.(01-31)
ddd 星期.(星期日).
Dddd 中文2.01版,同上.
ddddd 日期.(1996/12/20)
dddddd 日期.(1996年12月20日)
m 月份,前面不补0.(1-12)
mm 月份,前面补0.(01-12)
mmm 中文显示.(十二月)
mmmm 中文2.01版,同上.
Yy 年度.(00-99)
yyyy 年度.(0000-9999)
h 小时.(0-23)
hh 小时.(00-23)
n 分钟.(0-59)
nn 分钟.(00-59)
s 秒钟.(0-59)
ss 秒钟.(00-59)
t 时间.(09:20 PM)
tt 时间.(09:20:15 PM)
am/pm 单独显示am or pm.(若大写,则显示大写)
a/p 单独显示a or p.
范例
The following example assigns 'The meeting is on Wednesday, February 15, 1995 at 10:30 AM' to the string variable S.
S := FormatDateTime('"The meeting is on " dddd, mmmm d, yyyy, " at " hh:mm AM/PM',
StrToDateTime('2/15/95 10:30am'));//???
--------------------------------------------------------
Now 传回目前的日期时间.
--------------------------------------------------------
Unit SysUtils
函数原型 function Now: TDateTime;
范例
procedure TForm1.Button1Click(Sender: TObject);
begin
Label1.Caption := DateTimeToStr(Now);
end;
# Now, DateTimeToStr Example
--------------------------------------------------------
StrToDate 将字串转为TDateTime型态的日期.
--------------------------------------------------------
Unit SysUtils
函数原型 function StrToDate(const S: string): TDateTime;
范例 procedure TForm1.Button1Click(Sender: TObject);
var
ADate: TDateTime;
begin
ADate := StrToDate(Edit1.Text);
Label1.Caption := DateToStr(ADate);
end;
范例
procedure TForm1.Button1Click(Sender: TObject);
var
ADate: TDateTime;
days: array[1..7] of string;
begin
days[1] := 'Sunday';
days[2] := 'Monday';
days[3] := 'Tuesday';
days[4] := 'Wednesday';
days[5] := 'Thursday';
days[6] := 'Friday';
days[7] := 'Saturday';
ADate := StrToDate(Edit1.Text);
ShowMessage(Edit1.Text + ' is a ' + days[DayOfWeek(ADate)];
end;
# StrToDate, DayOfWeek Example
--------------------------------------------------------
StrToDateTime 将字串转为TDateTime型态的日期时间.
--------------------------------------------------------
Unit SysUtils
函数原型 function StrToDateTime(const S: string): TDateTime;
范例
procedure TForm1.Button1Click(Sender: TObject);
var
ADateAndTime: TDateTime;
begin
ADateAndTime := StrToDateTime(Edit1.Text);
Table1.FieldByName('TimeStamp').AsDateTime := ADateAndTime;
end;
--------------------------------------------------------
StrToTime 将字串转为TDateTime型态的时间.
--------------------------------------------------------
Unit SysUtils
函数原型 function StrToTime(const S: string): TDateTime;
范例
procedure TForm1.Button1Click(Sender: TObject);
var
ATime: TDateTime;
begin
ATime := StrToTime(Edit1.Text);
if ATime < 0.50 then
ShowMessage('Good Morning')
else
ShowMessage('Good Afternoon');
end;
--------------------------------------------------------
Time 传回目前的时间.
--------------------------------------------------------
Unit SysUtils
函数原型 function Time: TDateTime;
范例
procedure TForm1.Timer1Timer(Sender: TObject);
var
DateTime : TDateTime;
str : string;
begin
DateTime := Time; // store the current date and time
str := TimeToStr(DateTime); // convert the time into a string
Caption := str; // display the time on the form's caption
{ Note This could have been done with the following line of code:
Caption := TimeToStr(Time); }
end;
# Time, TimeToStr Example
--------------------------------------------------------
TimeToStr 时间转换成内定型字串.(09:20:15 PM)
--------------------------------------------------------
Unit SysUtils
函数原型 function TimeToStr(Time: TDateTime): string;
GetMem procedure 配置记忆体程序
New 配置指位器P的记忆体空间，
大小为P所指型态的大小.
--------------------------------------------------------
Dispose 释放New所配置的记忆体.
--------------------------------------------------------
Unit System
函数原型 procedure New(var P: Pointer);
函数原型 procedure Dispose(var P: Pointer);
范例 type
PListEntry = ^TListEntry;
TListEntry = record
Next: PListEntry;
Text: string;
Count: Integer;
end;
var
List, P: PListEntry;
begin
...
New(P);
P^.Next := List;
P^.Text := 'Hello world';
P^.Count := 1;
List := P;
...
Dispose(P);
…
end;
范例
type
Str18 = string[18];
var
P: ^Str18;
begin
New(P);
P^ := 'Now you see it...';
Dispose(P); { Now you don't... }
end;
--------------------------------------------------------
GetMem 配置指位器P的记忆体空间，大小可自行设定.
--------------------------------------------------------
范例
var
F: file;
Size: Integer;
Buffer: PChar;
begin
AssignFile(F, 'test.txt');
Reset(F, 1);
try
Size := FileSize(F);
GetMem(Buffer, Size);
try
BlockRead(F, Buffer^, Size);
ProcessFile(Buffer, Size);
finally
FreeMem(Buffer);
end;
finally
CloseFile(F);
end;
end;
--------------------------------------------------------
FreeMem 释放GetMem所配置的记忆体.
--------------------------------------------------------
Unit System
函数原型 procedure GetMem(var P: Pointer; Size: Integer);
函数原型 procedure FreeMem(var P: Pointer[; Size: Integer]);
范例 var
F: file;
Size: Integer;
Buffer: PChar;
begin
AssignFile(F, 'test.txt');
Reset(F, 1);
try
Size := FileSize(F);
GetMem(Buffer, Size);
try
BlockRead(F, Buffer^, Size);
ProcessFile(Buffer, Size);
finally
FreeMem(Buffer);
end;
finally
CloseFile(F);
end;
end;
====================================
File-management routines 档案管理常式
====================================
--------------------------------------------------------
ChangeFileExt 变更档案的副档名
--------------------------------------------------------
Unit SysUtils
函数原型 function ChangeFileExt(const FileName, Extension: string):
string;
范例 procedure TForm1.Button1Click(Sender: TObject);
var
S: String;
P1:String;
P2:String;
begin
P1:='abc.txt';
P2:='.ini';
S := ChangeFileExt(P1,P2);
Label1.Caption:=S;
end;
结果 S== 'abc.ini'
P1:='abc'
P2:='.ini'
S== 'abc.ini'
P1:='c:/windows/abc.txt'
P2:='.ini'
S=='c:/windows/abc.ini'
P1:='abc.txt'
P2:='ini'
S=='abcini'
**注意:P2的第一位元必须有一点'.ini'
范例
procedure TForm1.ConvertIcon2BitmapClick(Sender: TObject);
var
s : string;
Icon: TIcon;
begin
OpenDialog1.DefaultExt := '.ICO';
OpenDialog1.Filter := 'icons (*.ico)|*.ICO';
OpenDialog1.Options := [ofOverwritePrompt, ofFileMustExist, ofHideReadOnly ];
if OpenDialog1.Execute then
begin
Icon := TIcon.Create;
try
Icon.Loadfromfile(OpenDialog1.FileName);
s:= ChangeFileExt(OpenDialog1.FileName,'.BMP');
Image1.Width := Icon.Width;
Image1.Height := Icon.Height;
Image1.Canvas.Draw(0,0,Icon);
Image1.Picture.SaveToFile(s);
ShowMessage(OpenDialog1.FileName + ' Saved to ' + s);
finally
Icon.Free;
end;
end;
end;
# SaveToFile, Create, Height, Width, Canvas, ChangeFileExt example
--------------------------------------------------------
ExpandFileName 将档案名称加在目前所在之路径全名之後
--------------------------------------------------------
Unit SysUtils
函数原型 function ExpandFileName(const FileName: string): string;
说明 设目前目录为 c:/windows 档案名称为 abc.txt
则结果为 c:/windows/abc.txt
**** 此函数并不是求abc.txt的所在路径.
范例 procedure TForm1.Button1Click(Sender: TObject);
var
S: String;
begin
S:=ExpandFileName('abc.txt');
Label1.Caption:=S;
end;
范例
procedure TForm1.Button1Click(Sender: TObject)
begin
ListBox1.Items.Add(ExpandFileName(Edit1.Text));
end;
------------------------------------------------------------------
DirectoryExists 目录是否存在------------------------------------------------------------------
Unit
FileCtrl
uses FileCtrl;
procedure TForm1.Button1Click(Sender: TObject);
begin
if not DirectoryExists('c:/temp') then
if not CreateDir('C:/temp') then
raise Exception.Create('Cannot create c:/temp');
end;
--------------------------------------------------------
ForceDirectories 目录
---------------------------------------------------------
Unit FileCtrl
函数原型 function ForceDirectories(Dir: string): Boolean;
procedure TForm1.Button1Click(Sender: TObject);
var
Dir: string;
begin
Dir := 'C:/APPS/SALES/LOCAL';
if DirectoryExists(Dir) then
Label1.Caption := Dir + ' was created'
end;
--------------------------------------------------------
ExpandUNCFileName 同上(只是得到网路上的路径)
--------------------------------------------------------
Unit SysUtils
函数原型 function ExpandUNCFileName(const FileName: string):string;
ExtractFileDir 分析字串中的路径
Unit SysUtils
函数原型 function ExtractFileDir(const FileName: string): string;
说明 设S字串为 c:/windows/abc.txt
则结果为 c:/windows
**** 功能在於由任何部份传来的叁数,加以分析它的路径
范例 procedure TForm1.Button1Click(Sender: TObject);
var
S: String;
P1:String;
begin
P1:='c:/windows/abc.txt';
S:=ExtractFileDir(P1);
Label1.Caption:=S;
end;
S=='c:/windows'
P1:='abc.txt'
S=='
P1:='c:abc.txt'
S=='c:'
P1:='c:/abc.txt'
S=='c:/'
--------------------------------------------------------
ExtractFileDrive 分析字串中的磁碟机名称
--------------------------------------------------------
Unit SysUtils
函数原型 function ExtractFileDrive(const FileName: string): string;
**** 功能同上,只是传回磁碟机名称.
范例 procedure TForm1.Button1Click(Sender: TObject);
var
S: String;
P1:String;
begin
P1:='c:/windows/abc.txt';
S:=ExtractFileDrive(P1);
Label1.Caption:=S;
end;
S:='c:'
P1:='abc.txt'
S=='
--------------------------------------------------------
ExtractFileExt 分析字串中的档案名称的副档名
--------------------------------------------------------
Unit SysUtils
函数原型 function ExtractFileExt(const FileName: string): string;
范例 procedure TForm1.Button1Click(Sender: TObject);
var
S: String;
P1:String;
begin
P1:='c:/windows/abc.txt';
S:=ExtractFileExt(P1);
Label1.Caption:=S;
end;
S=='.txt'
P1:='c:/windows/abc'
S=='
范例 MyFilesExtension := ExtractFileExt(MyFileName);
--------------------------------------------------------
ExtractFileName 分析字串中的档案名称(只传回档案名称)
--------------------------------------------------------
Unit SysUtils
函数原型 function ExtractFileName(const FileName: string): string;
范例 procedure TForm1.Button1Click(Sender: TObject);
var
S: String;
P1:String;
begin
P1:='c:/windows/abc.txt';
S:=ExtractFileName(P1);
Label1.Caption:=S;
end;
S=='abc.txt'
范例
procedure TForm1.Button1Click(Sender: TObject);
var
BackupName: string;
FileHandle: Integer;
StringLen: Integer;
X: Integer;
Y: Integer;
begin
if SaveDialog1.Execute then
begin
if FileExists(SaveDialog1.FileName) then
begin
BackupName := ExtractFileName(SaveDialog1.FileName);
BackupName := ChangeFileExt(BackupName, '.BAK');
if not RenameFile(SaveDialog1.FileName, BackupName) then
raise Exception.Create('Unable to create backup file.');
end;
FileHandle := FileCreate(SaveDialog1.FileName);
{ Write out the number of rows and columns in the grid. }
FileWrite(FileHandle,
StringGrid1.ColCount, SizeOf(StringGrid1.ColCount));
FileWrite(FileHandle,
StringGrid1.RowCount, SizeOf(StringGrid1.RowCount));
for X := 0 to StringGrid1.ColCount ? 1 do
begin
for Y := 0 to StringGrid1.RowCount ? 1 do
begin
{ Write out the length of each string, followed by the string itself. }
StringLen := Length(StringGrid1.Cells[X,Y]);
FileWrite(FileHandle, StringLen, SizeOf(StringLen));
FileWrite(FileHandle,
StringGrid1.Cells[X,Y], Length(StringGrid1.Cells[X,Y]);
end;
end;
FileClose(FileHandle);
end;
end;
##FileExists, RenameFile, FileCreate, FileWrite, FileClose, ExtractFileName Example
--------------------------------------------------------
ExtractFilePath 分析字串中的路径
--------------------------------------------------------
Unit SysUtils
函数原型 function ExtractFilePath(const FileName: string): string;
说明 设S字串为 c:/windows/abc.txt
则结果为 c:/windows范例 procedure TForm1.Button1Click(Sender: TObject);
var
S: String;
P1:String;
begin
P1:='c:/windows/abc.txt';
S:=ExtractFilePath(P1);
Label1.Caption:=S;
end;
范例
begin
with Session do
begin
ConfigMode := cmSession;
try
AddStandardAlias('TEMPDB', ExtractFilePath(ParamStr(0)), 'PARADOX');
finally
ConfigMode := cmAll;
end;
end;
##ConfigMode, AddStandardAlias, ExtractFilePath example
--------------------------------------------------------
FileSearch 寻找档案在磁碟机中的正确路径
--------------------------------------------------------
Unit SysUtils
函数原型 function FileSearch(const Name, DirList: string): string;
范例 var
s:string;
begin
s:= FileSearch('abc.txt', 'c:/window/');
Label1.Caption:=s;
end;
说明 找到传回c:/window/abc.txt 找不到传回空字串.
范例
procedure TForm1.Button1Click(Sender: TObject);
var
buffer: array [0..255] of char;
FileToFind: string;
begin
GetWindowsDirectory(buffer, SizeOf(buffer));
FileToFind := FileSearch(Edit1.Text, GetCurrentDir + ';' + buffer);
if FileToFind = ' then
ShowMessage('Couldn't find ' + Edit1.Text + '.')
else
ShowMessage('Found ' + FileToFind + '.');
end;
##FileSearch, ShowMessage Example
--------------------------------------------------------
FileAge 传回档案的日期及时间(DOS型态).
--------------------------------------------------------
Unit SysUtils
函数原型 function FileAge(const FileName: string): Integer;
说明 就是档案总管中档案内容裹面的修改日期.
范例 procedure TForm1.Button1Click(Sender: TObject);
var
S: String;
FileDate1:Integer;
DateTime1:TDateTime;
begin
FileDate1 := FileAge('c:/delphi_d/delphi_help1.txt');
DateTime1 := FileDateToDateTime(FileDate1);
S := DateTimeToStr(DateTime1);
Label1.Caption:=S;
end;
--------------------------------------------------------
FileDateToDateTime 将DOS型态的日期时间转换为TDateTime型态.
--------------------------------------------------------
Unit SysUtils
函数原型 function FileDateToDateTime(FileDate: Integer):TDateTime;
-----------------------------------------------------------------------------
DateTimeToFileDate 将TDateTime型态的日期时间转换为 DOS型态.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function DateTimeToFileDate(DateTime: TDateTime):Integer;
FileGetDate 传回档案的日期及时间(DOS型态).
Unit SysUtils
函数原型 function FileGetDate(Handle: Integer): Integer;
说明 就是档案总管中档案内容裹面的修改日期.
范例 procedure TForm1.Button1Click(Sender: TObject);
var
FileHandle:Integer;
S: String;
FileDate1:Integer;
DateTime1:TDateTime;
begin
FileHandle :=FileOpen('c:/delphi_d/delphi_help2.txt',
fmOpenReadWrite);
if FileHandle > 0 then
Begin
FileDate1 := FileGetDate(FileHandle);
DateTime1 := FileDateToDateTime(FileDate1);
S := DateTimeToStr(DateTime1);
FileClose(FileHandle);
End
else
S := 'Open File Error';
Label1.Caption:=S;
end;
-----------------------------------------------------------------------------
FileSetDate 设定档案的日期及时间(DOS型态).
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function FileSetDate(Handle: Integer; Age: Integer): Integer;
说明 传回值为0表示成功.
-----------------------------------------------------------------------------
DeleteFile 删除档案
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function DeleteFile(const FileName: string): Boolean;
范例 一 DeleteFile('DELETE.ME');
范例 二 if FileExists(FileName) then
if MessageDlg('Do you really want to delete ' +
ExtractFileName(FileName) + '?'), []) = IDYes then
DeleteFile(FileName);
##FileExists, DeleteFile Example
-----------------------------------------------------------------------------
RenameFile 更改档名
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function RenameFile(const OldName, NewName: string):Boolean;
范例
procedure TForm1.Button1Click(Sender: TObject);
var
BackupName: string;
FileHandle: Integer;
StringLen: Integer;
X: Integer;
Y: Integer;
begin
if SaveDialog1.Execute then
begin
if FileExists(SaveDialog1.FileName) then
begin
BackupName := ExtractFileName(SaveDialog1.FileName);
BackupName := ChangeFileExt(BackupName, '.BAK');
if not RenameFile(SaveDialog1.FileName, BackupName) then
raise Exception.Create('Unable to create backup file.');
end;
FileHandle := FileCreate(SaveDialog1.FileName);
{ Write out the number of rows and columns in the grid. }
FileWrite(FileHandle,
StringGrid1.ColCount, SizeOf(StringGrid1.ColCount));
FileWrite(FileHandle,
StringGrid1.RowCount, SizeOf(StringGrid1.RowCount));
for X := 0 to StringGrid1.ColCount ? 1 do
begin
for Y := 0 to StringGrid1.RowCount ? 1 do
begin
{ Write out the length of each string, followed by the string itself. }
StringLen := Length(StringGrid1.Cells[X,Y]);
FileWrite(FileHandle, StringLen, SizeOf(StringLen));
FileWrite(FileHandle,
StringGrid1.Cells[X,Y], Length(StringGrid1.Cells[X,Y]);
end;
end;
FileClose(FileHandle);
end;
end;
-----------------------------------------------------------------------------
DiskFree 磁碟机剩馀空间(Bytes)
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function DiskFree(Drive: Byte): Integer;
范例 var
S: string;
begin
S := IntToStr(DiskFree(0) div 1024) + ' Kbytes free.';
Label1.Caption:=S;
end;
说明 Drive
0=目前磁碟机,1=A磁碟机,2=B磁碟机...传回值若为-1,表示磁碟机侦测错误.
范例
var
S: string;
AmtFree: Int64;
Total: Int64;
begin
AmtFree := DiskFree(0);
Total := DiskSize(0);
S := IntToStr(AmtFree div Total) + 'percent of the space on drive 0 is free: ' (AmtFree div 1024) + ' Kbytes free. ';
Canvas.TextOut(10, 10, S);
end;
##DiskFree, DiskSize Example
-----------------------------------------------------------------------------
DiskSize 磁碟机空间大小(Bytes)
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function DiskSize(Drive: Byte): Integer;
范例 var
S: string;
begin
S := IntToStr(DiskSize(0) div 1024) + ' Kbytes free.';
Label1.Caption:=S;
end;
说明 Drive
0=目前磁碟机,1=A磁碟机,2=B磁碟机....传回值若为-1,表示磁碟机侦测错误.
##DiskFree, DiskSize Example
-----------------------------------------------------------------------------
FileExists 判断档案是否存在.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function FileExists(const FileName: string): Boolean;
类似 FileExists, RenameFile, FileCreate, FileWrite, FileClose, ExtractFileName Example
范例
procedure TForm1.Button1Click(Sender: TObject);
var
BackupName: string;
FileHandle: Integer;
StringLen: Integer;
X: Integer;
Y: Integer;
begin
if SaveDialog1.Execute then
begin
if FileExists(SaveDialog1.FileName) then
begin
BackupName := ExtractFileName(SaveDialog1.FileName);
BackupName := ChangeFileExt(BackupName, '.BAK');
if not RenameFile(SaveDialog1.FileName, BackupName) then
raise Exception.Create('Unable to create backup file.');
end;
FileHandle := FileCreate(SaveDialog1.FileName);
{ Write out the number of rows and columns in the grid. }
FileWrite(FileHandle,
StringGrid1.ColCount, SizeOf(StringGrid1.ColCount));
FileWrite(FileHandle,
StringGrid1.RowCount, SizeOf(StringGrid1.RowCount));
for X := 0 to StringGrid1.ColCount ? 1 do
begin
for Y := 0 to StringGrid1.RowCount ? 1 do
begin
{ Write out the length of each string, followed by the string itself. }
StringLen := Length(StringGrid1.Cells[X,Y]);
FileWrite(FileHandle, StringLen, SizeOf(StringLen));
FileWrite(FileHandle,
StringGrid1.Cells[X,Y], Length(StringGrid1.Cells[X,Y]);
end;
end;
FileClose(FileHandle);
end;
end;
##FileExists, DeleteFile Example
##FileExists, RenameFile, FileCreate, FileWrite, FileClose, ExtractFileName Example
-----------------------------------------------------------------------------
FileOpen 开档.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function FileOpen(const FileName: string; Mode:
Integer):Integer;
**** 开档失败传回-1.
说明 以下有关档案读取都属低阶,如Dos Int 21h中有关档案的部
分.
fmOpenRead = $0000;
fmOpenWrite = $0001;
fmOpenReadWrite = $0002;
fmShareCompat = $0000;
fmShareExclusive = $0010;
fmShareDenyWrite = $0020;
fmShareDenyRead = $0030;
fmShareDenyNone = $0040;
fmOpenRead Open for read access only.
FmOpenWrite Open for write access only.
FmOpenReadWrite Open for read and write access.
fmShareCompat Compatible with the way FCBs are
opened.
fmShareExclusive Read and write access is denied.
fmShareDenyWrite Write access is denied.
fmShareDenyRead Read access is denied.
fmShareDenyNone Allows full access for others.
范例
procedure OpenForShare(const FileName: String);
var
FileHandle : Integer;
begin
FileHandle := FileOpen(FileName, fmOpenWrite or fmShareDenyNone);
if FileHandle > 0 then
{valid file handle}
else
{Open error: FileHandle = negative DOS error code}
end;
范例
procedure TForm1.Button1Click(Sender: TObject);
var
iFileHandle: Integer;
iFileLength: Integer;
iBytesRead: Integer;
Buffer: PChar;
i: Integer
begin
if OpenDialog1.Execute then
begin
try
iFileHandle := FileOpen(OpenDialog1.FileName, fmOpenRead);
iFileLength := FileSeek(iFileHandle,0,2);
FileSeek(iFileHandle,0,0);
Buffer := PChar(AllocMem(iFileLength + 1));
iBytesRead = FileRead(iFileHandle, Buffer, iFileLength);
FileClose(iFileHandle);
for i := 0 to iBytesRead-1 do
begin
StringGrid1.RowCount := StringGrid1.RowCount + 1;
StringGrid1.Cells[1,i+1] := Buffer[i];
StringGrid1.Cells[2,i+1] := IntToStr(Integer(Buffer[i]));
end;
finally
FreeMem(Buffer);
end;
end;
end;
##FileOpen, FileSeek, FileRead Example
-----------------------------------------------------------------------------
FileCreate 建档
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function FileCreate(const FileName: string): Integer;
范例
procedure TForm1.Button1Click(Sender: TObject);
var
BackupName: string;
FileHandle: Integer;
StringLen: Integer;
X: Integer;
Y: Integer;
begin
if SaveDialog1.Execute then
begin
if FileExists(SaveDialog1.FileName) then
begin
BackupName := ExtractFileName(SaveDialog1.FileName);
BackupName := ChangeFileExt(BackupName, '.BAK');
if not RenameFile(SaveDialog1.FileName, BackupName) then
raise Exception.Create('Unable to create backup file.');
end;
FileHandle := FileCreate(SaveDialog1.FileName);
{ Write out the number of rows and columns in the grid. }
FileWrite(FileHandle,
StringGrid1.ColCount, SizeOf(StringGrid1.ColCount));
FileWrite(FileHandle,
StringGrid1.RowCount, SizeOf(StringGrid1.RowCount));
for X := 0 to StringGrid1.ColCount ? 1 do
begin
for Y := 0 to StringGrid1.RowCount ? 1 do
begin
{ Write out the length of each string, followed by the string itself. }
StringLen := Length(StringGrid1.Cells[X,Y]);
FileWrite(FileHandle, StringLen, SizeOf(StringLen));
FileWrite(FileHandle,
StringGrid1.Cells[X,Y], Length(StringGrid1.Cells[X,Y]);
end;
end;
FileClose(FileHandle);
end;
end;
##FileExists, RenameFile, FileCreate, FileWrite, FileClose, ExtractFileName Example
-----------------------------------------------------------------------------
FileClose 关档
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 procedure FileClose(Handle: Integer);
范例
procedure TForm1.Button1Click(Sender: TObject);
var
BackupName: string;
FileHandle: Integer;
StringLen: Integer;
X: Integer;
Y: Integer;
begin
if SaveDialog1.Execute then
begin
if FileExists(SaveDialog1.FileName) then
begin
BackupName := ExtractFileName(SaveDialog1.FileName);
BackupName := ChangeFileExt(BackupName, '.BAK');
if not RenameFile(SaveDialog1.FileName, BackupName) then
raise Exception.Create('Unable to create backup file.');
end;
FileHandle := FileCreate(SaveDialog1.FileName);
{ Write out the number of rows and columns in the grid. }
FileWrite(FileHandle,
StringGrid1.ColCount, SizeOf(StringGrid1.ColCount));
FileWrite(FileHandle,
StringGrid1.RowCount, SizeOf(StringGrid1.RowCount));
for X := 0 to StringGrid1.ColCount ? 1 do
begin
for Y := 0 to StringGrid1.RowCount ? 1 do
begin
{ Write out the length of each string, followed by the string itself. }
StringLen := Length(StringGrid1.Cells[X,Y]);
FileWrite(FileHandle, StringLen, SizeOf(StringLen));
FileWrite(FileHandle,
StringGrid1.Cells[X,Y], Length(StringGrid1.Cells[X,Y]);
end;
end;
FileClose(FileHandle);
end;
end;
##FileExists, RenameFile, FileCreate, FileWrite, FileClose, ExtractFileName Example
============================================
**** 它是以Handle为叁数.
============================================
FileRead 读取档案
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function FileRead(Handle: Integer; var Buffer; Count: Integer):Integer;
范例
procedure TForm1.Button1Click(Sender: TObject);
var
iFileHandle: Integer;
iFileLength: Integer;
iBytesRead: Integer;
Buffer: PChar;
i: Integer
begin
if OpenDialog1.Execute then
begin
try
iFileHandle := FileOpen(OpenDialog1.FileName, fmOpenRead);
iFileLength := FileSeek(iFileHandle,0,2);
FileSeek(iFileHandle,0,0);
Buffer := PChar(AllocMem(iFileLength + 1));
iBytesRead = FileRead(iFileHandle, Buffer, iFileLength);
FileClose(iFileHandle);
for i := 0 to iBytesRead-1 do
begin
StringGrid1.RowCount := StringGrid1.RowCount + 1;
StringGrid1.Cells[1,i+1] := Buffer[i];
StringGrid1.Cells[2,i+1] := IntToStr(Integer(Buffer[i]));
end;
finally
FreeMem(Buffer);
end;
end;
end;
##FileOpen, FileSeek, FileRead Example
-----------------------------------------------------------------------------
FileWrite 写入档案
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function FileWrite(Handle: Integer; const Buffer; Count: Integer): Integer;
范例
procedure TForm1.Button1Click(Sender: TObject);
var
BackupName: string;
FileHandle: Integer;
StringLen: Integer;
X: Integer;
Y: Integer;
begin
if SaveDialog1.Execute then
begin
if FileExists(SaveDialog1.FileName) then
begin
BackupName := ExtractFileName(SaveDialog1.FileName);
BackupName := ChangeFileExt(BackupName, '.BAK');
if not RenameFile(SaveDialog1.FileName, BackupName) then
raise Exception.Create('Unable to create backup file.');
end;
FileHandle := FileCreate(SaveDialog1.FileName);
{ Write out the number of rows and columns in the grid. }
FileWrite(FileHandle,
StringGrid1.ColCount, SizeOf(StringGrid1.ColCount));
FileWrite(FileHandle,
StringGrid1.RowCount, SizeOf(StringGrid1.RowCount));
for X := 0 to StringGrid1.ColCount do
begin
for Y := 0 to StringGrid1.RowCount do
begin
{ Write out the length of each string, followed by the string itself. }
StringLen := Length(StringGrid1.Cells[X,Y]);
FileWrite(FileHandle, StringLen, SizeOf(StringLen));
FileWrite(FileHandle,
StringGrid1.Cells[X,Y], Length(StringGrid1.Cells[X,Y]);//?????????/
end;
end;
FileClose(FileHandle);
end;
end;
##FileExists, RenameFile, FileCreate, FileWrite, FileClose, ExtractFileName Example
-----------------------------------------------------------------------------
FileSeek 移动档案指标位置
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function FileSeek(Handle, Offset, Origin: Integer): Integer;
说明 Origin=0读/写指标由档案开头算起.
Origin=1读/写指标由目前位置算起.
Origin=2读/写指标移动到档案结束处.
**** 功能与Dos Int 21h 插断 42h 的功能相同.
失败传回-1.
范例 procedure TForm1.Button1Click(Sender: TObject);
var
FileHandle : Integer;
FileName : String;
Buffer : PChar;
S : String;
ReadBytes : Integer;
begin
FileName:='c:/delphi_test/abc.ttt';
S:='1234567890';
if FileExists(FileName) then
FileHandle := FileOpen(FileName, fmOpenReadWrite)
else
FileHandle := FileCreate(FileName);
if FileHandle < 0 then
Begin
MessageDlg('开档失败', mtInformation, [mbOk], 0);
Exit;
End;
GetMem(Buffer, 100);
try
StrPCopy(Buffer, S);
FileWrite(FileHandle,Buffer^,10);
FileSeek(FileHandle,4,0);
ReadBytes:=FileRead(FileHandle, Buffer^, 100);
Buffer[ReadBytes]:=#0;
Label1.Caption:=IntToStr(ReadBytes)+' '+
StrPas(Buffer);
finally
FreeMem(Buffer);
end;
FileClose(FileHandle);
end;
结果 存档後abc.ttt共有1234567890等十个Bytes.
从第五位元开始读取,共读取六个位元.
567890
(位移是从0开始算起)
procedure TForm1.Button1Click(Sender: TObject);
var
iFileHandle: Integer;
iFileLength: Integer;
iBytesRead: Integer;
Buffer: PChar;
i: Integer
begin
if OpenDialog1.Execute then
begin
try
iFileHandle := FileOpen(OpenDialog1.FileName, fmOpenRead);
iFileLength := FileSeek(iFileHandle,0,2);
FileSeek(iFileHandle,0,0);
Buffer := PChar(AllocMem(iFileLength + 1));
iBytesRead = FileRead(iFileHandle, Buffer, iFileLength);
FileClose(iFileHandle);
for i := 0 to iBytesRead-1 do
begin
StringGrid1.RowCount := StringGrid1.RowCount + 1;
StringGrid1.Cells[1,i+1] := Buffer[i];
StringGrid1.Cells[2,i+1] := IntToStr(Integer(Buffer[i]));
end;
finally
FreeMem(Buffer);
end;
end;
end;
##FileOpen, FileSeek, FileRead Example
-----------------------------------------------------------------------------
FileGetAttr 档案属性
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function FileGetAttr(const FileName: string): Integer;
说明 faReadOnly = $00000001;
faHidden = $00000002;
faSysFile = $00000004;
faVolumeID = $00000008;
faDirectory = $00000010;
faArchive = $00000020;
faAnyFile = $0000003F;
范例 procedure TForm1.Button1Click(Sender: TObject);
var
S: String;
begin
S:=IntToStr(FileGetAttr('c:/delphi_d/delphi_help1.txt'));
Label1.Caption := S;
end;
-----------------------------------------------------------------------------
FileSetAttr 设定档案属性
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function FileSetAttr(const FileName: string; Attr: Integer):
Integer;
说明 设定成功传回0
-----------------------------------------------------------------------------
FindClose 结束FindFirst/FindNext
-----------------------------------------------------------------------------
procedure TForm1.Button1Click(Sender: TObject);
var
sr: TSearchRec;
FileAttrs: Integer;
begin
StringGrid1.RowCount := 1;
if CheckBox1.Checked then
FileAttrs := faReadOnly
else
FileAttrs := 0;
if CheckBox2.Checked then
FileAttrs := FileAttrs + faHidden;
if CheckBox3.Checked then
FileAttrs := FileAttrs + faSysFile;
if CheckBox4.Checked then
FileAttrs := FileAttrs + faVolumeID;
if CheckBox5.Checked then
FileAttrs := FileAttrs + faDirectory;
if CheckBox6.Checked then
FileAttrs := FileAttrs + faArchive;
if CheckBox7.Checked then
FileAttrs := FileAttrs + faAnyFile;
if FindFirst(Edit1.Text, FileAttrs, sr) = 0 then
begin
with StringGrid1 do
begin
if (sr.Attr and FileAttrs) = sr.Attr then
begin
Cells[1,RowCount-1] := sr.Name;
Cells[2,RowCount-1] := IntToStr(sr.Size);
end;
while FindNext(sr) = 0 do
begin
if (sr.Attr and FileAttrs) = sr.Attr then
begin
RowCount := RowCount + 1;
Cells[1, RowCount-1] := sr.Name;
Cells[2, RowCount-1] := IntToStr(sr.Size);
end;
end;
FindClose(sr);
end;
end;
end;
##FindFirst, FindNext, FindClose Example
-----------------------------------------------------------------------------
FindFirst 寻找第一个符合的档案.
-----------------------------------------------------------------------------
procedure TForm1.Button1Click(Sender: TObject);
var
sr: TSearchRec;
FileAttrs: Integer;
begin
StringGrid1.RowCount := 1;
if CheckBox1.Checked then
FileAttrs := faReadOnly
else
FileAttrs := 0;
if CheckBox2.Checked then
FileAttrs := FileAttrs + faHidden;
if CheckBox3.Checked then
FileAttrs := FileAttrs + faSysFile;
if CheckBox4.Checked then
FileAttrs := FileAttrs + faVolumeID;
if CheckBox5.Checked then
FileAttrs := FileAttrs + faDirectory;
if CheckBox6.Checked then
FileAttrs := FileAttrs + faArchive;
if CheckBox7.Checked then
FileAttrs := FileAttrs + faAnyFile;
if FindFirst(Edit1.Text, FileAttrs, sr) = 0 then
begin
with StringGrid1 do
begin
if (sr.Attr and FileAttrs) = sr.Attr then
begin
Cells[1,RowCount-1] := sr.Name;
Cells[2,RowCount-1] := IntToStr(sr.Size);
end;
while FindNext(sr) = 0 do
begin
if (sr.Attr and FileAttrs) = sr.Attr then
begin
RowCount := RowCount + 1;
Cells[1, RowCount-1] := sr.Name;
Cells[2, RowCount-1] := IntToStr(sr.Size);
end;
end;
FindClose(sr);
end;
end;
end;
##FindFirst, FindNext, FindClose Example
-----------------------------------------------------------------------------
FindNext 寻找下一个符合的档案.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 procedure FindClose(var F: TSearchRec);
函数原型 function FindFirst(const Path: string; Attr: Integer;
var F: TSearchRec): Integer;
函数原型 function FindNext(var F: TSearchRec): Integer;
说明 成功传回0
范例 var
SRec: TSearchRec;
procedure TForm1.SearchClick(Sender: TObject);
begin
FindFirst('c:/delphi/bin/*.*', faAnyFile, SRec);
Label1.Caption := SRec.Name + ' is ' + IntToStr(SRec.Size) +
' bytes in size';
end;
procedure TForm1.AgainClick(Sender: TObject);
begin
FindNext(SRec);
Label1.Caption := SRec.Name + ' is ' + IntToStr(SRec.Size) +
' bytes in size';
end;
procedure TForm1.FormClose(Sender: TObject);
begin
FindClose(SRec);
end
TSearchRec = record
Time: Integer;
Size: Integer;
Attr: Integer;
Name: TFileName;
xcludeAttr: Integer;
FindHandle: THandle;
FindData: TWin32FindData;
end;
============================================
Floating-point conversion routines 浮点数转换函式
============================================
FloatToDecimal 将浮点数转换为十进位数.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 procedure FloatToDecimal(var Result: TFloatRec; const Value;
ValueType: TFloatValue; Precision, Decimals: Integer);
-----------------------------------------------------------------------------
FloatToStrF 将浮点数转换为格式化字串.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function FloatToStrF(Value: Extended; Format: TFloatFormat;
Precision,Digits: Integer): string;
-----------------------------------------------------------------------------
FloatToStr 将浮点数转换为字串.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function FloatToStr(Value: Extended): string;
-----------------------------------------------------------------------------
FloatToText 将浮点数转换为格式化十进位.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function FloatToText(Buffer: PChar; const Value; ValueType:
TFloatValue;Format: TFloatFormat; Precision, Digits:
Integer): Integer;
-----------------------------------------------------------------------------
FloatToTextFmt 将浮点数转换为格式化十进位.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function FloatToTextFmt(Buffer: PChar; const Value;
ValueType: TFloatValue; Format: PChar): Integer;
-----------------------------------------------------------------------------
FormatFloat 将浮点数转换为格式化字串.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function FormatFloat(const Format: string; Value: Extended):
string;
-----------------------------------------------------------------------------
StrToFloat 将字串转换为浮点数.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function StrToFloat(const S: string): Extended;
范例 procedure TForm1.Button1Click(Sender: TObject);
var
Value:Double;
S:String;
begin
S:=' 1234.56 ';
Value:=StrToFloat(S);
Label1.Caption:=Format('转换为 [%9.3f]',[Value]);
end;
注意 若S字串含有非数字字元,会产生错误讯号.
-----------------------------------------------------------------------------
TextToFloat 将 null-terminated 字串转换为浮点数.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function TextToFloat(Buffer: PChar; var Value; ValueType:
TFloatValue): Boolean;
===========================================
Flow-control routines 流程控制常式
===========================================
Break 从 for, while, or repeat 终止跳出.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure Break;
范例 var
S: string;
begin
while True do
begin
ReadLn(S);
try
if S = ' then Break;
WriteLn(S);
finally
{ do something for all cases }
end;
end;
end;
-----------------------------------------------------------------------------
Continue 从 for, while, or repeat 继续执行.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure Continue;
范例 var
F: File;
i: integer;
begin
for i := 0 to (FileListBox1.Items.Count - 1) do
begin
try
if FileListBox1.Selected[i] then
begin
if not FileExists(FileListBox1.Items.Strings[i]) then
begin
MessageDlg('File: ' +FileListBox1.Items.Strings[i]
+ ' not found', mtError, [mbOk], 0);
Continue;
end;
AssignFile(F, FileListBox1.Items.Strings[i]);
Reset(F, 1);
ListBox1.Items.Add(IntToStr(FileSize(F)));
CloseFile(F);
end;
finally
{ do something here }
end;
end;
end;
范例
var
F: File;
i: Integer;
begin
for i := 0 to (FileListBox1.Items.Count - 1) do begin
try
if FileListBox1.Selected[i] then
begin
if not FileExists(FileListBox1.Items.Strings[i]) then begin
MessageDlg('File: ' + FileListBox1.Items.Strings[i] +
' not found', mtError, [mbOk], 0);
Continue;
end;
AssignFile(F, FileListBox1.Items.Strings[i]);
Reset(F, 1);
ListBox1.Items.Add(IntToStr(FileSize(F)));
CloseFile(F);
end;
finally
{ do something here }
end;
end;
end;
## Continue, Items, Selected Example
-----------------------------------------------------------------------------
Exit 直接离开一个程序.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure Exit;
-----------------------------------------------------------------------------
Halt 结束程式返回作业系统.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure Halt [ ( Exitcode: Integer) ];
范例 begin
if 1 = 1 then
begin
if 2 = 2 then
begin
if 3 = 3 then
begin
Halt(1); { Halt right here! }
end;
end;
end;
Canvas.TextOut(10, 10, 'This will not be executed');
end;
-----------------------------------------------------------------------------
RunError 停止程式执行且执行run-time error.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure RunError [ ( Errorcode: Byte ) ];
范例 begin
{$IFDEF Debug}
if P = nil then
RunError(204);
{$ENDIF}
end;
=====================================
I/O routines I