我有2个或更多的动态字符串数组填充一些巨大的数据,我想将这个2数组合并到一个数组,我知道我可以用一个for循环这样做：
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;
但是在巨大的数据上是缓慢的,是否有更快的方式像复制数组内存数据？
解决方法
您可以使用内置的Move功能将内存块移动到另一个位置.参数是源和目标内存块和要移动的数据的大小.
由于您正在复制字符串,源数组在合并后必须通过将其填充为零来销毁.否则,对于字符串的引用将会在程序中造成破坏和破坏.
var
Arr1,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;