Difficulty understanding loops over bars and SetAsArray

[aya3adel]

Hello Folks,

I have several issues as a newbie in mql5:

1- problem understanding how loops work and how to access the latest bar and the bars before it (is the index of the previous bar i+1 or i-1 how to decide),

2-does SetAsArray function affects how the loop works also are the user defined arrays and indicator buffers timeseries or normal arrays

3- if I want to code lets say moving average is it better to start from the oldest bar to the newest or it doesn't matter

As far as I understand that the latest bar index is set to 0 and the oldest bar index is rates total-1 however when I try to print out this it comes the other way around (the latest bar index is rates total-1 and the oldest bar index is 0)

I've read this topic but it made me more confused actually http:  Range not behaving as expected - Heiken Ashi - MQL4 and MetaTrader 4 - MQL4 programming forum (mql5.com)

Sorry for being long but I'm new to mql5 and help is truly appreciated

Regards.

[William Roeder]

1. It is up to you. Would you rather think of the chart [oldest … newest] as [0 … ratesTotal-1] (non-series/previous is i-1) or [ratesTotal-1 … 0] (as-series/previous is i+1).
2. Set all your arrays and buffers per № 1.
3. Doesn't matter.
4. The latest bar is not zero. It is up to you. See № 1.
5. You are confused, because there are two ways and it is up to you.
             How to do your lookbacks correctly #9 - #14 & #19

[aya3adel]

William Roeder:

1. It is up to you. Would you rather think of the chart [oldest … newest] as [0 … ratesTotal-1] (non-series/previous is i-1) or [ratesTotal-1 … 0] (as-series/previous is i+1).
2. Set all your arrays and buffers per № 1.
3. Doesn't matter.
4. The latest bar is not zero. It is up to you. See № 1.
5. You are confused, because there are two ways and it is up to you.
             How to do your lookbacks correctly #9 - #14 & #19

Thank you so much William that really cleared everything up. Highly appreciating your help.