SysUtils.StrCopy、SysUtils.StrECopy
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SysUtils.StrCopy、SysUtils.StrECopy
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
posted on 2008-05-12 21:21 万一 阅读(5030) 评论(1) 编辑 收藏
标签:PChar,arr,ABC,p3,StrECopy,SysUtils,StrCopy 来源: https://blog.51cto.com/u_14617575/2746267