Delphi出现“Unsatisfied forward or external declaration”错误分析

  今天在操作与“汉字转拼音”有关的程序编写时,总是提示“Unsatisfied forward or external declaration”错误,最终发现是如下原因造成的:

type

TForm1 = class(TForm)

  ...

function GetPYIndexChar(hzchar:string):char; //函数声明

private

{ Private declarations }

public

{ Public declarations }

end;

var

Form1: TForm1;

implementation

{$R *.dfm}

// 获取指定汉字的拼音索引字母函数,如:“汉”的索引字母是“H”

function GetPYIndexChar(hzchar:string):char;  //Error,出错了!

begin

case WORD(hzchar[1]) shl 8 + WORD(hzchar[2]) of

$B0A1..$B0C4 : result := 'A';

$B0C5..$B2C0 : result := 'B';

$B2C1..$B4ED : result := 'C';

$B4EE..$B6E9 : result := 'D';

$B6EA..$B7A1 : result := 'E';

$B7A2..$B8C0 : result := 'F';

$B8C1..$B9FD : result := 'G';

$B9FE..$BBF6 : result := 'H';

$BBF7..$BFA5 : result := 'J';

$BFA6..$C0AB : result := 'K';

$C0AC..$C2E7 : result := 'L';

$C2E8..$C4C2 : result := 'M';

$C4C3..$C5B5 : result := 'N';

$C5B6..$C5BD : result := 'O';

$C5BE..$C6D9 : result := 'P';

$C6DA..$C8BA : result := 'Q';

$C8BB..$C8F5 : result := 'R';

$C8F6..$CBF9 : result := 'S';

$CBFA..$CDD9 : result := 'T';

$CDDA..$CEF3 : result := 'W';

$CEF4..$D188 : result := 'X';

$D1B9..$D4D0 : result := 'Y';

$D4D1..$D7F9 : result := 'Z';

else result := char(0);

end; //结束Case

end; //结束GetPYIndexChar函数

分析:其实错误原因很简单,Delphi的函数声明与实现部分并非完全一样的,因为Delphi的实现部分中要加

入本函数归谁所有,因此改后代码如下:

type

TForm1 = class(TForm)

  ...

function GetPYIndexChar(hzchar:string):char; //函数声明

private

{ Private declarations }

public

{ Public declarations }

end;

var

Form1: TForm1;

implementation

{$R *.dfm}

// 获取指定汉字的拼音索引字母函数,如:“汉”的索引字母是“H”

function TForm1.GetPYIndexChar(hzchar:string):char;  //只需加个TForm1就OK了呵呵!

begin

case WORD(hzchar[1]) shl 8 + WORD(hzchar[2]) of

$B0A1..$B0C4 : result := 'A';

$B0C5..$B2C0 : result := 'B';

$B2C1..$B4ED : result := 'C';

$B4EE..$B6E9 : result := 'D';

$B6EA..$B7A1 : result := 'E';

$B7A2..$B8C0 : result := 'F';

$B8C1..$B9FD : result := 'G';

$B9FE..$BBF6 : result := 'H';

$BBF7..$BFA5 : result := 'J';

$BFA6..$C0AB : result := 'K';

$C0AC..$C2E7 : result := 'L';

$C2E8..$C4C2 : result := 'M';

$C4C3..$C5B5 : result := 'N';

$C5B6..$C5BD : result := 'O';

$C5BE..$C6D9 : result := 'P';

$C6DA..$C8BA : result := 'Q';

$C8BB..$C8F5 : result := 'R';

$C8F6..$CBF9 : result := 'S';

$CBFA..$CDD9 : result := 'T';

$CDDA..$CEF3 : result := 'W';

$CEF4..$D188 : result := 'X';

$D1B9..$D4D0 : result := 'Y';

$D4D1..$D7F9 : result := 'Z';

else result := char(0);

end; //结束Case

end; //结束GetPYIndexChar函数