delphi 使用TArray.Sort对数组排序

默认排序比较类

您可以使用TArray.Sort对数组进行排序。

对数字数组进行排序的示例

uses

System.Generics.Collections, System.Generics.Defaults;

var

Values: array[0..8] of Integer = (1,3,5,7,9,8,6,2,4);

I: Integer;

begin

TArray.Sort(Values);

for I in Values do

Write(I);

end.

执行结果

123456789

字符串数组排序示例

uses

System.Generics.Collections, System.Generics.Defaults;

var

Values: array[0..3] of string = ('Carol', 'Bob', 'Alice', 'Dave');

S: string;

begin

TArray.Sort(Values);

for S in Values do

WriteLn(S);

end.

执行结果

Alice

Bob

Carol

Dave

通过在继承自IComparer的类中指定比较方法来进行排序

通过将继承IComparer的类指定为TArray.Sort的第二个参数，可以在任何条件下对数组进行排序。

记录用于示例代码。

type

TMyRecord = record

I: Integer;

S: string;

end;

按TMYRECORD的I字段递增顺序排序的示例

比较类，以降序对TMyRecord的I字段进行排序

type

TMyRecordComparer1 = class(TComparer)

public

function Compare(const Left, Right: TMyRecord): Integer; override;

end;

function TMyRecordComparer1.Compare(const Left, Right: TMyRecord): Integer;

begin

Result := (Right.I - Left.I);

end;

样例程序

var

Values: array[0..3] of TMyRecord = (

(I: 1; S: 'Carol'),

(I: 3; S: 'Bob'),

(I: 4; S: 'Alice'),

(I: 2; S: 'Dave')

);

R: TMyRecord;

begin

TArray.Sort(Values, TMyRecordComparer1.Create);

for R in Values do

WriteLn(Format('%d:%s', [R.I, R.S]));

end.

执行结果

4:Alice

3:Bob

2:Dave

1:Carol

TMYRECORD的S字段的升序排序示例

比较类，该类按升序对TMyRecord的S字段进行排序

type

TMyRecordComparer2 = class(TComparer)

public

function Compare(const Left, Right: TMyRecord): Integer; override;

end;

function TMyRecordComparer2.Compare(const Left, Right: TMyRecord): Integer;

begin

Result := System.SysUtils.CompareStr(Left.S, Right.S);

end;

样例程序

var

Values: array[0..3] of TMyRecord = (

(I: 1; S: 'Carol'),

(I: 3; S: 'Bob'),

(I: 4; S: 'Alice'),

(I: 2; S: 'Dave')

);

R: TMyRecord;

begin

TArray.Sort(Values, TMyRecordComparer2.Create);

for R in Values do

WriteLn(Format('%d:%s', [R.I, R.S]));

end.

执行结果

4:Alice

3:Bob

1:Carol

2:Dave

通过委托给回调例程对比较进行排序

System.Generics.Defaults.TDelegatedComparer类将比较过程委托给回调例程。

TMYRECORD的S字段的升序排序示例

var

Values: array[0..3] of TMyRecord = (

(I: 1; S: 'Carol'),

(I: 3; S: 'Bob'),

(I: 4; S: 'Alice'),

(I: 2; S: 'Dave')

);

R: TMyRecord;

begin

TArray.Sort(Values, TDelegatedComparer.Construct(

function(const Left, Right: TMyRecord): Integer

begin

Result := System.SysUtils.CompareStr(Left.S, Right.S);

end

));

for R in Values do

WriteLn(Format('%d:%s', [R.I, R.S]));

end.

执行结果

4:Alice

3:Bob

1:Carol

2:Dave

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