Trader’s Tech – Writing Your Own EA Part 75 – Arrays

Forex Robot

Whew! It might actually be cooling in northern Texas a little bit. That’ll be nice.

If you’re new to this series and want to check it out from the beginning, you can find that here. And look here for a list of all the programming articles.

In Part 74, we talked about the ArrayCopySeries() function and I digressed somewhat with a discussion of trade volumes on the MT4 platform. Here we’ll discuss some additional series and other multi-dimensional array functions.

int ArrayDimension(object array[])) – this function will return the number of dimensions for which the object array[] is dimensioned.

This would be handy if you wanted to write a function that performed a calculation on the array that was passed. The function could be written to handle multiple dimensions making it much more versatile.

bool ArrayGetAsSeries(object array[]) – this function will test your array and return a true if the array is organized as a series array (indexed top to bottom.)

bool ArrayIsSeries(object array[]) – this function will return true if the array is actually a series array (Time[],Open[],Close[],High[],Low[], or Volume[].)

The difference between a series/series-organized array and a regular array is that there is no memory set aside for a series array, the data is stored in the same memory location that the actual price data is stored. Because it’s actual rate data, a series array cannot be initialized with different values.

bool ArraySetAsSeries(double&array[], bool set) – this function will set the indexing direction of the array. “If the set parameter has the TRUE value, the array will be indexed in a reversed order, i.e., the last element has a zero index. The FALSE value sets a standard indexing order. The function returns the previous status. ” Quoted from here.

And that’s a wrap on arrays. Next time we’ll revisit our discussion of chart drawing objects and some tricks I use in their placement.

Thanks for your attention and please follow me on Twitter and LinkedIn.

Tim

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