如何在 c# 中复制数组元素并使用 Array.Copy() 反转某些元素？

Question

Elements of SourceArray are being copied to 2 separate Arrays namely DestArray1 and DestArray2.

output:

• DestArray1 will have the first 4 elements of SourceArray but in the reverse form [4 3 2 1]
• DestArray2 will have the last 4 elements of SourceArray. [5 6 7 8]

I want to replace the for loop with Array.Copy() method

if not reversed then Array.Copy() works kind of fine except for the last element, but to copy with reverse, it seems the Array.Copy doesn't work or I am not able to implement it.

int i, j;
int bytelength =8;
int halfbytelength = 4;

byte[] SourceArray = new byte[]{ 1, 2, 3, 4, 5, 6, 7, 8 };
byte[] DestArray1 = new byte[4];
byte[] DestArray2 = new byte[4];

for (i = halfbytelength - 1, j = 0; i >= 0; i -= 1, j++)
 {
   DestArray1[j] = SourceArray[i];
 }
for (i = halfbytelength; i < bytelength; i += 1)
{
  DestArray2[i - halfbytelength] = SourceArray[i];
}

I tried following the code but the results are not as expected as seen in(Results:), is there a way to do it?

Array.Copy(SourceArray, 0, DestArray1, 3, 0);
Array.Copy(SourceArray, 4, DestArray2, 0, 3);

Result:
DestArray1: [0 0 0 0]
DestArray2: [5 6 7 0]

Answer 1

First array.

To reverse array you can just call Array.Reverse() after copying:

Array.Copy(SourceArray, 0, DestArray1, 0, 4);
Array.Reverse(DestArray1);

Second array.

if not reversed then Array.Copy() works kind of fine except for the last element

Because you pass invalid count of elements to copy (last parameter):

Array.Copy(SourceArray, 4, DestArray2, 0, 3); // 3 - elements count, not an index

Simply replace 3 with 4:

Array.Copy(SourceArray, 4, DestArray2, 0, 4); // 4 and it will copy including the last element