关于指针初始化的问题 - 回复"下雨天2"

问题来源: http://www.cnblogs.com/del/archive/2008/05/02/1179416.html#1179645

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一个全局变量可以初始化, 如果你不主动初始化, 也会被自动初始化;
一个局部变量不能被初始化, 虽然你不能主动初始化, 但它会被赋予一个随机值.

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unit Unit1;interfaceuses  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,  Dialogs, StdCtrls;type  TForm1 = class(TForm)    procedure FormCreate(Sender: TObject);  end;var  Form1: TForm1;implementation{$R *.dfm}var  i1: Integer; {会被自动初始化为 0}  p1: Pointer; {会被自动初始化为 0, 也就是空指针}const  BoolStr: array[Boolean] of string = ('False','True');procedure TForm1.FormCreate(Sender: TObject);var  i2: Integer; {会被初始化为一个随机值}  p2: Pointer; {会被初始化为一个随机地址}  b: Boolean;begin  ShowMessage(IntToStr(i1));          {0}  ShowMessage(IntToStr(i2));          {14909552}  ShowMessage(IntToStr(Integer(p1))); {0}  ShowMessage(IntToStr(Integer(p2))); {4570636}  {判断 p1、p2 两个指针是否是已赋值}  b := Assigned(p1);  ShowMessage(BoolStr[b]);  {False}  b := Assigned(p2);  ShowMessage(BoolStr[b]);  {True}  {释放指针后再判断}  p1 := nil;  p2 := nil;  b := Assigned(p1);  ShowMessage(BoolStr[b]);  {False}  b := Assigned(p2);  ShowMessage(BoolStr[b]);  {False}end;end.