# Datastructures

How to impelement list of element in micro such arduino and how to calculate its size !? need sd card or eeprom!? when I call elementKey The program have to return me values of A,B,C,D,E

You will not be able to keep 4000 elements in memory on a Micro, regardless of what type of memory you plan to use.

So, you will need an SD card.

I can't tell from your picture what the values in the cells are.

PaulS:
So, you will need an SD card.

Depending on the usage a SD card or EEPROM might be a bad idea. Get yourself a 23LC1024 128kB SPI SRAM or similar.

each value may be in range of (0 to 7)
to handle it in 8 bit

So this is read-only then? The micro has 2.5k of SRAM and 32k of Flash. With numbers from 0-7 you'll need at least 8k (5 columns, 3 bit each = 15 bit per row, so 2 bytes. Multiply that by 4000 and you know how much memory you need). If this is read-only data, you can store that in the internal flash. For read and write data get yourself a spi sram. If you know the distribution from 0-7, you can apply a per row compression. Compression rate will be better for larger chunks, so you might be able to squeeze it in the internal SRAM (but it's unlikely).

so how to implement this
I have solution to array of structs. each row considered as struct
and acessing them using any mechanism but I feel this not effiecient!?

alaamomen9:
so how to implement this
I have solution to array of structs. each row considered as struct
and acessing them using any mechanism but I feel this not effiecient!?

Why do you feel that way? Do you need time or memory efficiency?

I think it's better to use multidimentional Array instead if array of structs "less complex"
but I cannot figure out How !
you understand me?

alaamomen9:
I think it's better to use multidimentional Array instead if array of structs "less complex"
but I cannot figure out How !
you understand me?

This will create a 2d array with 4000 rows and 5 columns. Access to the 1234th row's C column is also shown.

byte data[4000][5];
byte value = data[1233][2]

But you won't be able to do that, unless you have 20k of sram.

oh you are right ,thanks sir