如何合并在Delphi 2字符串数组 [英] How to merge 2 string array in Delphi

问题描述

我有2个或多个动态字符串数组，一些巨大的数据填充，我想这2个数组合并成一个数组，我知道我可以用它做了这样的循环：

I have 2 or more dynamic string array that fill with some huge data , i want to merge this 2 array to one array , i know i can do it with a for loop like this :

var
  Arr1, Arr2, MergedArr: Array of string;
  I: Integer;
begin
  // Arr1:= 5000000 records
  // Arr2:= 5000000 records

  // Fill MergedArr by Arr1
  MergedArr:= Arr1;

  // Set length of MergedArr to length of ( Arra1 + Arr2 )+ 2
  SetLength(MergedArr, High(Arr1)+ High(Arr2)+2);

  // Add Arr2 to MergedArr
  for I := Low(Arr2)+1 to High(Arr2)+1 do
    MergedArr[High(Arr1)+ i]:= Arr2[i-1];
end;

但它是巨大的数据速度慢，有没有像数组复制内存中的数据更快的方法？

but it is slow on huge data , is there faster way like copy array memory data ?

推荐答案

您可以使用内置其中移动的内存块到另一个位置移动的功能。参数是源和目标存储块和大小要移动的数据。

You can use built-in Move function which moves a block of memory to another location. Parameters are source and target memory blocks and size of data to be moved.

由于要复制字符串，源阵列必须合并后用零填充它们摧毁。否则，对于字符串引用计数将全部错在后面的程序造成破坏和毁灭。

Because you are copying strings, source arrays must be destroyed after the merging by filling them with zeroes. Otherwise refcounts for strings will be all wrong causing havoc and destruction later in the program.

var
  Arr1, Arr2, MergedArr: Array of string;
  I: Integer;
begin
  SetLength(Arr1, 5000000);
  for I := Low(Arr1) to High(Arr1) do
    Arr1[I] := IntToStr(I);

  SetLength(Arr2, 5000000);
  for I := Low(Arr2) to High(Arr2) do
    Arr2[I] := IntToStr(I);

  // Set length of MergedArr to length of ( Arra1 + Arr2 )+ 2
  SetLength(MergedArr, High(Arr1)+ High(Arr2)+2);

  // Add Arr1 to MergedArr
  Move(Arr1[Low(Arr1)], MergedArr[Low(MergedArr)], Length(Arr1)*SizeOf(Arr1[0]));

  // Add Arr2 to MergedArr
  Move(Arr2[Low(Arr2)], MergedArr[High(Arr1)+1], Length(Arr2)*SizeOf(Arr2[0]));

  // Cleanup Arr1 and Arr2 without touching string refcount.
  FillChar(Arr1[Low(Arr1)], Length(Arr1)*SizeOf(Arr1[0]), 0);
  FillChar(Arr2[Low(Arr2)], Length(Arr2)*SizeOf(Arr2[0]), 0);

  // Test
  for I := Low(Arr1) to High(Arr1) do begin
    Assert(MergedArr[I] = IntToStr(I));
    Assert(MergedArr[I] = MergedArr[Length(Arr1) + I]);
  end;

  // Clear the array to see if something is wrong with refcounts
  for I := Low(MergedArr) to High(MergedArr) do
    MergedArr[I] := '';
end;

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