Nested For Loop MQL4

External question — Stack Overflow Stack Exchange Author: gershgorin Original post: https://stackoverflow.com/questions/71316227 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. I have an array which has the same size as the number of bars in my chart. I want to create a cumulative array that sums them up 200 at a time. I am trying to wrap my head around loops, and I'm not sure what I'm doing wrong. Array[] denotes the array that has the same number of bars as the chart. CumulativeSumArray[] is the array in which each value is the sum of 200 of the values of Array[] . I am attempting to accomplish this task via nested for loops. Here is a hypothetical situation: double Array[]; double CumulativeSumArray[]; Length=200; int i; int j; double _CumulativeSumArray; for(i=Bars-Length-1;i>=0;i--) { for(j=i,j>=i+Length;j++) { _CumulativeSumArray += Array[j]; } CumulativeSumArray[i]=_CumulativeSumArray; } What I end up getting with this loop, or at least what it looks like, is a cumulative sum of the whole array.

External answer — Stack Overflow Stack Exchange Author: user3666197 Original post: https://stackoverflow.com/a/71317053 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. Q : " not sure what I'm doing wrong. " A : ( Overhead-costs + Efficiency ) MQL4/5 code-execution eco-system works differently for Script, EA and even way more strange for CustomIndicator : Setup- costs ( hopefully not spent more than once ) Update- costs ( best kept as low as possible, just smart-update per tick ) Maintenance- costs ( best kept as low as possible, just smart-update per aNewBar ) So, best forget the full-depth tandem-loops straight now : Be it in start(){...} or OnInit(){...} , setup the values in Array[] and start filling the CumulativeSumArray[] ... progressively and state-fully : ArrayCopy( CumulativeSumArray, // destination Array, // source 0, // start 0, // start WHOLE_ARRAY ); // scope for( int fwdBarNUMBER = Bars - 1; fwdBarNUMBER > Bars - 201; fwdBarNUMBER-- ) CumulativeSumArray[fwdBarNUMBER] += CumulativeSumArray[fwdBarNUMBER - 1]; for( int fwdBarNUMBER = Bars - 201; fwdBarNUMBER >= 0; fwdBarNUMBER-- ) CumulativeSumArray[fwdBarNUMBER] += CumulativeSumArray[fwdBarNUMBER - 1] - CumulativeSumArray[fwdBarNUMBER - 201]; Given this pre-fill, an onNewBar() maintenance is as easy as: Array[1] = ... update your value on now last known Close[1] & other var. parts CumulativeSumArray[1] = CumulativeSumArray[ 2] + Array[1] - CumulativeSumArray[202]; // CumSum update and similarly you keep updating the "hot"-end of the running bar inside an OnTick(){...} -handler for EA-s or inside an if ( RefreshRates() ){...} -POSACK-ed code-block as: Array[0] = ... update your value on a so far known Close[0] CumulativeSumArray[0] = CumulativeSumArray[ 1] + Array[0] - CumulativeSumArray[201];

External answer — Stack Overflow Stack Exchange Author: PaulB Original post: https://stackoverflow.com/a/71322354 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. It should just be a case of getting your logic right for the loops you require. Try the following code double Array[]; double CumulativeSumArray[]; int Length=200; int idx=0; for(int i=Bars-1; i>=0; i-=Length) { for(int j=i; j>i-Length; j--) CumulativeSumArray[idx]+=Array[j]; idx++; }