Question

我正在尝试使用TFPGmap创建和使用一个简单的字典：

program rnTFPGmap; 
{$mode objfpc}
uses fgl; 

var 
    mydict: specialize TFPGmap<string, string>; 
    key: string; 
    i: longint; 

begin
    mydict.create; 
    mydict.add('k1','v1'); 
    mydict.add('k2','v2');
    mydict.add('k3','v3');
    //for key in mydict.keys do   {does not work either;}
    for i := 1 to length(mydict) do  {line 17: first error from here. }
        writeln(mydict[i]); 
end.

但是，它给出了以下错误：

$ fpc soq_rntfpgmap
Free Pascal Compiler version 3.0.0+dfsg-11+deb9u1 [2017/06/10] for x86_64
Copyright (c) 1993-2015 by Florian Klaempfl and others
Target OS: Linux for x86-64
Compiling soq_rntfpgmap.pas
soq_rntfpgmap.pas(17,16) Error: Type mismatch
soq_rntfpgmap.pas(18,19) Error: Incompatible type for arg no. 1: Got "LongInt", expected "ShortString"
soq_rntfpgmap.pas(22) Fatal: There were 2 errors compiling module, stopping
Fatal: Compilation aborted
Error: /usr/bin/ppcx64 returned an error exitcode

编辑：我试图根据文档修改代码，并提出了以下版本：

program rnTFPGmap; 
{$mode objfpc}
uses fgl; 
type 
    tuple = specialize TFPGmap<string, string>; 
    mydict = Array of tuple;
var 
    dict: mydict; 
    i: tuple; 
    item: string; 
begin
    setlength(dict, length(dict)+3); 
    dict.add('k1','v1');   {error on this line: "CREATE" expected but "ADD" found}
    dict.add('k2','v2');
    dict.add('k3','v3');
    writeln('dict.count: ', dict.count); 
    for i in dict do    
            writeln(i); 
end.

但是我现在遇到以下错误：

$ fpc soq_rntfpgmap
Free Pascal Compiler version 3.0.0+dfsg-11+deb9u1 [2017/06/10] for x86_64
Copyright (c) 1993-2015 by Florian Klaempfl and others
Target OS: Linux for x86-64
Compiling soq_rntfpgmap.pas
soq_rntfpgmap.pas(13,25) Warning: Variable "dict" of a managed type does not seem to be initialized
soq_rntfpgmap.pas(14,7) Fatal: Syntax error, "CREATE" expected but "ADD" found
Fatal: Compilation aborted
Error: /usr/bin/ppcx64 returned an error exitcode

无法解决此问题。

Answer 1

以下代码有效。请参阅注释以获取一些解释：

program rnTFPGmap; 
{$mode objfpc}
uses fgl; 
type 
    Rndict = specialize TFPGmap<string, string>;{define type under type}
var 
    dict: Rndict;               {define object under var}
    i: integer; 
{main: }
begin
    dict := Rndict.Create;      {create object in main}
    dict.add('k1','v1'); 
    dict.add('k2','v2'); 
    dict.add('k3','v3'); 
    for i := 0 to (dict.count-1) do begin 
        writeln('i: ',i, '; key: ', dict.getkey(i), '; value: ', dict.getdata(i)); 
        end; 
end.

输出：

i: 0; key: k1; value: v1
i: 1; key: k2; value: v2
i: 2; key: k3; value: v3

感谢@DavidHeffernan的指导。

为什么我不能在这里创建简单的字典

1 个答案: