StrCopy 和 StrECopy 都是复制源 PChar 串到目标 PChar 串, 只是返回值不同;
StrCopy 返回结果的首地址, StrECopy 返回结果的尾(#0)地址.
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;
type
TForm1 = class(TForm)
Button1: TButton;
Button2: TButton;
Button3: TButton;
Button4: TButton;
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
procedure Button3Click(Sender: TObject);
procedure Button4Click(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
//一般用法, 看不出 StrCopy 与 StrECopy 的区别
procedure TForm1.Button1Click(Sender: TObject);
var
arr: array[0..3] of Char; {假如 PChar 长度是 3, 这里数组要大出一个, PChar 最后还有一个 #0}
begin
StrCopy(arr, 'ABC');
ShowMessage(arr); {ABC}
StrCopy(arr, '123');
ShowMessage(arr); {123}
StrECopy(arr, 'ABC');
ShowMessage(arr); {ABC}
StrECopy(arr, '123');
ShowMessage(arr); {123}
end;
//测试 StrCopy 及其返回值:
procedure TForm1.Button2Click(Sender: TObject);
var
p1,p2,p3,p: PChar;
begin
p1 := '123456789';
p2 := 'ABC';
p3 := PChar(StringOfChar(#0, 9)); {这里用 StringOfChar 代替了 GetMem}
p := StrCopy(p3, p1);
ShowMessageFmt('%s, %s', [p3, p]); {123456789, 123456789}
p := StrCopy(p3, p2);
ShowMessageFmt('%s, %s', [p3, p]); {ABC, ABC}
ShowMessageFmt('%s, %s', [p3+4, p+4]); {56789, 56789}
end;
//测试 StrECopy 及其返回值:
procedure TForm1.Button3Click(Sender: TObject);
var
p1,p2,p3,p: PChar;
begin
p1 := '123456789';
p2 := 'ABC';
p3 := PChar(StringOfChar(#0, 9)); {这里用 StringOfChar 代替了 GetMem}
p := StrECopy(p3, p1);
ShowMessageFmt('%s, %s', [p3, p]); {123456789, }
p := StrECopy(p3, p2);
ShowMessageFmt('%s, %s', [p3, p+1]); {ABC, 56789}
end;
//可以巧妙利用 StrECopy 的返回值:
procedure TForm1.Button4Click(Sender: TObject);
var
p: PChar;
begin
GetMem(p, 10);
StrECopy(StrECopy(p,'12345'), '67890');
ShowMessage(p); {1234567890}
FreeMem(p);
end;
end.
SysUtils 单元下的公用函数目录