Delphi System.Delete 从字符串中删除指定的字符

Delphi System.Delete - 从字符串中删除指定的字符

原型：

procedure   _Delete{ var s : openstring; index, count : Integer };
asm
{     ->EAX     Pointer to s    }
{       EDX     index           }
{       ECX     count           }

        PUSH    ESI
        PUSH    EDI

        MOV     EDI,EAX

        XOR     EAX,EAX
        MOV     AL,[EDI]

{      如果index不在[1..Length（s）]中，则不执行任何操作    }

        TEST    EDX,EDX
        JLE     @@exit
        CMP     EDX,EAX
        JG      @@exit

{       将计数限制为[0..Length（s）-index+1]     }

        TEST    ECX,ECX
        JLE     @@exit
        SUB     EAX,EDX         { 计算长度-index+1       }
        INC     EAX
        CMP     ECX,EAX
        JLE     @@1
        MOV     ECX,EAX
@@1:
        SUB     [EDI],CL        { 按计数减少长度                   }
        ADD     EDI,EDX         {将EDI指向要删除的第一个字符 }
        LEA     ESI,[EDI+ECX]   { 将ESI指向要保留的第一个字符      }
        SUB     EAX,ECX         { #字符=长度（s）-索引+1-计数       }
        MOV     ECX,EAX

        REP     MOVSB

@@exit:
        POP     EDI
        POP     ESI
end;

procedure       _LStrDelete{ var s : AnsiString; index, count : Integer };
asm
        {     ->EAX     Pointer to s    }
        {       EDX     index           }
        {       ECX     count           }

        PUSH    EBX
        PUSH    ESI
        PUSH    EDI

        MOV     EBX,EAX
        MOV     ESI,EDX
        MOV     EDI,ECX

        CALL    UniqueString

        MOV     EDX,[EBX]
        TEST    EDX,EDX         { source already empty: nothing to do   }
        JE      @@exit

        MOV     ECX,[EDX-skew].StrRec.length

{       make index 0-based, if not in [0 .. Length(s)-1] do nothing     }

        DEC     ESI
        JL      @@exit
        CMP     ESI,ECX
        JGE     @@exit

{       limit count to [0 .. Length(s) - index] }

        TEST    EDI,EDI
        JLE     @@exit
        SUB     ECX,ESI         { ECX = Length(s) - index       }
        CMP     EDI,ECX
        JLE     @@1
        MOV     EDI,ECX
@@1:

{       move length - index - count characters from s+index+count to s+index }

        SUB     ECX,EDI         { ECX = Length(s) - index - count       }
        ADD     EDX,ESI         { EDX = s+index                 }
        LEA     EAX,[EDX+EDI]   { EAX = s+index+count           }
        CALL    Move

{       set length(s) to length(s) - count      }

        MOV     EDX,[EBX]
        MOV     EAX,EBX
        MOV     EDX,[EDX-skew].StrRec.length
        SUB     EDX,EDI
        CALL    _LStrSetLength

@@exit:
        POP     EDI
        POP     ESI
        POP     EBX
end;

procedure _WStrDelete(var S: WideString; Index, Count: Integer);
var
  L, N: Integer;
  NewStr: PWideChar;
begin
  L := Length(S);
  if (L > 0) and (Index >= 1) and (Index <= L) and (Count > 0) then
  begin
    Dec(Index);
    N := L - Index - Count;
    if N < 0 then N := 0;
    if (Index = 0) and (N = 0) then NewStr := nil else
    begin
      NewStr := _NewWideString(Index + N);
      if Index > 0 then
        Move(Pointer(S)^, NewStr^, Index * 2);
      if N > 0 then
        Move(PWideChar(Pointer(S))[L - N], NewStr[Index], N * 2);
    end;
    WStrSet(S, NewStr);
  end;
end;

参数说明：

• s   //要处理的源字符串
• index   //起始位置;  起始位置不能小于 1
• count　//结束长度（要删除的字符数）　

示例：

var
  sStr: string;
begin
  sStr := 'TaoRoy 2022';
  Delete(sStr, 7, 5);
  ShowMessage(sStr); {TaoRoy}
end;

　　

创建时间：2022.07.07