@Joe Riel Thank you

@Carl Love Thank you:)

@Kitonum Thank you, It worked.

@Joe Riel ok,Thank you

@Kitonum Thank you

@Kitonum Thank you~~

@Carl Love Thank you very much.

@Carl Love Thank you ~~~

@vv Yes, convert to list. Thank you very much.

@Carl Love  Thank you very much...:)

@Carl Love  if I only want to change certain bit number in the first block with the second block, second with third block, third with fourth block, and the last block back to first block, then what can i do?

@John Fredsted thank you again, but what i want is I only want to crossover the certain bit in one block with another block. for example: the code as below,

for i from 1 to 4 do  // execute for block 1 until block 4

for j from 3 to 5 do  // crossover certain bit with the next block
block[i][j]:=block[i+1][j];

end do; end do;

original block:  [0,0,1,1,0,0,1], [0,0,1,1,1,0,0],[0,1,0,1,0,1,0], [1,0,0,1,1,1,0]

The output for the first block might be like this: in this case the third bit until the fifth bit in the first block will crossover with the third bit until the fifth bit in the second block. 

By using the code I write above, i manage to get the output as below:

block[1]:=[0,0,1,1,1,0,1]  

block[2]:=[0,0,0,1,0,0,0]

block[3]:=[0,1,0,1,1,1,0]

block[4]:=[1,0,block[5][3],block[5][4],block[5][5],1,0] // error occur because i dont have the fifth block in the original block. 

So what i need is the last block will crossover with the third bit until the fifth bit in the first block. So, what can I do?

@Doug Meade  This work. I can get the output I want. 

@ThU Sry for disturbing again, it's work but sometime will get same value for x and y. any method can solve this problem? x must be less than y, not equal.

@John Fredsted  Thank you