# Smaller array equal to Subarray of Larger array **URL:** \ **Category:** Programming\ **Tags:** automation-studio\ **Created:** [November 18, 2024, 12:49pm UTC](https://community.br-automation.com/t/smaller-array-equal-to-subarray-of-larger-array/4930 "2024-11-18T12:49:55Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![adamkujawinski](https://dub1.discourse-cdn.com/brcommunity/user_avatar/community.br-automation.com/adamkujawinski/32/4007_2.png) [@adamkujawinski](https://community.br-automation.com/u/adamkujawinski)\ **Post date:** [November 18, 2024, 12:49pm UTC](https://community.br-automation.com/t/smaller-array-equal-to-subarray-of-larger-array/4930/1 "2024-11-18T12:49:55Z")
I have a larger array example of x as type usint[0..99] which contains certain addresses I want to isolate. It would be extremely convenient to do any one of the following as the array masking is varies Option 1 y as type usint[4..5] y := x // where y[4..5] = x[4..5] Option 2 y as type usint[0..1] y := x[4..5] // where y[0..1] = x[4..5] Option 3 y as type uint y := x[4..5] // where y = usint[2] to uint is it correct that masking and Subarrays are not supported in Automation Studio? I’m trying to avoid multiple lines to take larger data sets. We have a series of parameters which range from one bit to 64 bytes and their address in an array vary depending on the machine used so being able to change a few enumerators would be quite an advantage. ---
**Author:** ![tommi.piiparinen](https://dub1.discourse-cdn.com/brcommunity/user_avatar/community.br-automation.com/tommi.piiparinen/32/2183_2.png) [@tommi.piiparinen](https://community.br-automation.com/u/tommi.piiparinen)\ **Post date:** [November 18, 2024, 1:16pm UTC](https://community.br-automation.com/t/smaller-array-equal-to-subarray-of-larger-array/4930/2 "2024-11-18T13:16:48Z")
Two suggestions for you depending on whether you want to copy the data, or just use a pointer to it. Both of them work with all of your Option variants. Copy the data to a new variable. (Data in y is only updated when this line is executed, changing value in y does not affect x). ```auto brsmemcpy(ADR(y), ADR(x[4]), SIZEOF(y)); ``` Use pointers. Define y as what you want as a “reference” and use the following line. (Data is updated in y as soon as it is updated in x. Changing values in y will also change it in x) ```auto y ACCESS ADR(x[4]); ``` Example code below: Variable definitions ![image](https://europe1.discourse-cdn.com/brcommunity/original/2X/6/68c3d7c322a69368cb2c5d825fab9356e03e4c11.png) Code: ```auto PROGRAM _INIT // Preset example data FOR i := 0 TO 99 DO x[i] := i; END_FOR; END_PROGRAM PROGRAM _CYCLIC // Option by copying to new variable brsmemcpy(ADR(y), ADR(x[4]), SIZEOF(y)); // Different options with pointers Option1 ACCESS ADR(x[4]); Option2 ACCESS ADR(x[4]); Option3 ACCESS ADR(x[4]); END_PROGRAM ``` Values in Watch ![image](https://europe1.discourse-cdn.com/brcommunity/original/2X/a/a26041e34bbef0b8f4993e960f9ff0a4c7a166ec.png) ---
**Author:** ![adamkujawinski](https://dub1.discourse-cdn.com/brcommunity/user_avatar/community.br-automation.com/adamkujawinski/32/4007_2.png) [@adamkujawinski](https://community.br-automation.com/u/adamkujawinski)\ **Post date:** [November 18, 2024, 2:41pm UTC](https://community.br-automation.com/t/smaller-array-equal-to-subarray-of-larger-array/4930/3 "2024-11-18T14:41:22Z")
Your solution works great, and was exactly what I was looking for in the original post. That being said, I have now raised another concern. After some “I swear I did that already”, my issue seems to have come from referencing within a structure. ![image](https://europe1.discourse-cdn.com/brcommunity/original/2X/c/c2b10893c41da641085f8325b26641b3339fa275.png) ![image](https://europe1.discourse-cdn.com/brcommunity/original/2X/0/0d93b4cbdcbb2ce85eb37648e9321207217cb388.png) ```auto //Works y ACCESS ADR(x[4]); // Does not work z.y ACCESS ADR(x[4]); ``` just as an added bonus, referencing z does not work either. Error 1392: Dynamic Variable required for Access ---
**Author:** ![marcusbnr](https://dub1.discourse-cdn.com/brcommunity/user_avatar/community.br-automation.com/marcusbnr/32/256_2.png) [@marcusbnr](https://community.br-automation.com/u/marcusbnr)\ **Post date:** [November 18, 2024, 3:40pm UTC](https://community.br-automation.com/t/smaller-array-equal-to-subarray-of-larger-array/4930/4 "2024-11-18T15:40:51Z")
Hi Adam, Unfortunately, it is not possible to do this. You can’t include a dynamic variable as part of a structure (at least within IEC languages like Structured Text). The entire structure would have to be dynamic. Your options are: 1. Use a non-structure variable to reference a non-structure variable 2. Use a non-structure variable to reference a member of a structure variable 3. Use a structure variable to reference a structure variable Something you could do is make the variable z.y a UDINT and store the address you want to reference: > z.y = ADR(x[4]) However this isn’t a dynamic variable which means you’d then have to either pass this address into a function, or access it with another dynamic variable (residing outside of a structure). ---
**Author:** ![adamkujawinski](https://dub1.discourse-cdn.com/brcommunity/user_avatar/community.br-automation.com/adamkujawinski/32/4007_2.png) [@adamkujawinski](https://community.br-automation.com/u/adamkujawinski)\ **Post date:** [November 18, 2024, 3:49pm UTC](https://community.br-automation.com/t/smaller-array-equal-to-subarray-of-larger-array/4930/5 "2024-11-18T15:49:46Z")
> [@marcusbnr](#): > > You can’t include a dynamic variable as part of a structure (at least within IEC languages like Structured Text) > > 1. Use a non-structure variable to reference a non-structure variable > 2. Use a non-structure variable to reference a member of a structure variable > 3. Use a structure variable to reference a structure variable I did not achieve success when all of my variables were set to dynamic within the structure. So the third Option you suggested was tested and at the very least, I have not had any success. I decided to use a non-structured pointer to reference a structured variable as my solution. ---
**Author:** ![marcusbnr](https://dub1.discourse-cdn.com/brcommunity/user_avatar/community.br-automation.com/marcusbnr/32/256_2.png) [@marcusbnr](https://community.br-automation.com/u/marcusbnr)\ **Post date:** [November 18, 2024, 4:16pm UTC](https://community.br-automation.com/t/smaller-array-equal-to-subarray-of-larger-array/4930/6 "2024-11-18T16:16:23Z")
Sorry if that was unclear. You can use a variable of a _structure type_ to reference another variable of the same structure type. You cannot reference anything with a structure _member_. Glad you have a working solution though!