Delphi 查找字符串中的下划线

Question

我有两个名为“ver1”和“ver2”的字符串，字符串中的输入如下所示：

Ver1: B2CD1 Ver2: B3A10

有时看起来像这样：

Ver1: B2CD1_A1 Ver2: B3A10_DE

我的问题：如何在其中的“_”后的两个字符串中搜索它的 return 值？

顺便说一句，该功能用于软件版本比较。请只在我的问题中给我建议，而不是我的全部功能。

谢谢

uses
  Classes, SysUtils, StrUtils, Forms, Controls, Graphics, Dialogs, StdCtrls;


type

  { TForm1 }

  TForm1 = class(TForm)
    Button1: TButton;
    Edit1: TEdit;
    Edit2: TEdit;
    Memo1: TMemo;
    procedure Button1Click(Sender: TObject);
    procedure Edit1Change(Sender: TObject);
    procedure Memo1Change(Sender: TObject);
  private

  public

  end;

var
  Form1: TForm1;

implementation

{$R *.lfm}

function isSoftwareGreater(ver1,ver2 : string) : byte;
var i : integer;
    tmp1,tmp2 : string;
    cver1,cver2 : int64;

begin
{
  Return values:
      0: versions are equal
      1: ver1 is bigger then ver2
      2: ver2 is bigger then ver1
    253: ver1 is too big (could not be converted to int64)
    254: ver2 is too big (could not be converted to int64)
}

  tmp1 := '';
  tmp2 := '';

  for i := 1 to length(ver1) do
   begin
    if (ver1[i] in ['a'..'z']) or (ver1[i] in ['A'..'Z']) then
     tmp1 := tmp1 + inttostr(Ord(ver1[i]));
    if (ver1[i] in ['0'..'9']) then
     tmp1 := tmp1 + ver1[i];
   end;
  for i := 1 to length(ver2) do
   begin
    if (ver2[i] in ['a'..'z']) or (ver2[i] in ['A'..'Z']) then
     tmp2 := tmp2 + inttostr(Ord(ver2[i]));
    if (ver2[i] in ['0'..'9']) then
     tmp2 := tmp2 + ver2[i];
   end;

  if not TryStrToInt64(tmp2,cver2) then
   begin
    isSoftwareGreater := 254;
    exit;
   end;
  if not TryStrToInt64(tmp1,cver1) then
   begin
    isSoftwareGreater := 253;
    exit;
   end;

  if ver1 > ver2 then
    isSoftwareGreater := 1
  else if ver2 > ver1 then
    isSoftwareGreater := 2
  else if ver1 = ver2 then
    isSoftwareGreater := 0;

end;

Answer 1

您可以使用 Pos() function 搜索字符串。它 returns 找到的字符的索引，如果没有找到则为 0。

var
    Index     : Integer;
    SubString : String;
begin
    Index := Pos('_', Ver1);
    if Index > 0 then
        SubString := Copy(Ver1, Index + 1, MAXINT)
    else
        SubString := '';
end;

如果您想提取两个标记之间的文本，您必须如上所示搜索第一个，然后搜索第二个，从第一个标记之后开始。 Pos() 有一个可选的第三个参数来指定从哪里开始搜索。这给出：

var
    Index1    : Integer;
    Index2    : Integer;
    SubString : String;
begin
    Index1 := Pos('_', Ver1);
    if Index1 > 0 then begin
        Index2 := Pos('_', Ver1, Index1 + 1);
        if Index2 > 0 then
            // We have two underscore, extract text between them
            SubString := Copy(Ver1, Index1 + 1, Index2 - Index1 - 1)
        else
            // Only one underscore, extract text from the first to the end of string
            SubString := Copy(Ver1, Index1 + 1, MAXINT);
    end
    else
        SubString := '';
end;

Answer 2

您可以使用ContainsStr()检查字符串是否有'_'，然后使用SubString()和IndexOf()

function GetString(const AString, ASubString: string): string;
begin
  Result:= EmptyStr;
  if ContainsStr(AString, ASubString) then
    Result:= AString.Substring(Astring.IndexOf(ASubString)+1, AString.Length);
end;

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