How does one use a counter variable in ThinkScript?

We have several examples of this scattered throughout the site. Some are found in our free video tutorials and others are found right here in the Q&A forum. However they are difficult to find if that is the exact term you are searching for.

So here is how to create a counter, based on the true/false variable from your code VAOPerigee.

rec counter = if VAOPerigee then 1 else if counter[1] == 1 or counter[1] < 3 then counter[1] + 1 else 0;

The biggest concept to grasp when moving from any other programing language to a Trading platform is to realize the platform runs a loop. It loops through every bar of the chart, every time a price is updated or the chart is refreshed. For each iteration of that loop (of which you have no control) the platform will read and execute each line of your code.

So that single line of code uses recursion. At each candle on the chart, it checks if VAOPerigee is true. If true, it resets the value of counter to 1. If false, it first checks if the previous candle value of counter is less than 3 (but NOT equal zero). If so, it increments the value of counter by one. Otherwise it sets counter to zero.

Now we create your long signal

def LongSignal = counter == 3;

And we’re done.

So the reason we do not   code it

rec counter=if VAOPergee then 1 else if counter [1]< 3 then counter[1]+1 else 0;

or

rec counter=if   VAOPerigee then counter[1] +1;

is because counter array is not initialized to 0 like in a normal language, correct? and it can not be initialized since you can not separate the first iteration like other languages.

You are saying counter[1] or even counter[0] could be any number, even a non-integer number or at  least a negative integer or a positive # greater than 3 .   That is why we can not do it like this which is the common way I believe done in NinjaScript or MTL4  or etc . We must set these 2 elements of the the array named counter[1]   & counter[0],  and then we can accumulate.

This code does it marvelously.

if you could do this in Thinkscript, which you can not do.

declare first iteration;(does not exist)

def counter=0;def counter[1]=0;   or def  array counter[] =0;

counter=counter+1; or rec counter=if VAOPerigee then counter[1] +1;  normal code for accumulating would work.

This is another way to write it. This method uses nested if-then-else statements to accomplish the exact same thing as:

rec counter = if VAOPerigee then 1 else if counter[1] == 1 or counter[1] < 3 then counter[1] + 1 else 0;

It may be easier to read for those who are used to a C-based programing language.

rec counter;
if (VAOPerigee == yes) {
# we have a signal, set counter to 1
counter = 1;
} else {
if (counter[1] == 1 or counter[1] < 3) {
# previous value of counter indicates a signal has occurred
# increment counter by one
counter = counter[1] + 1;
} else {
# no signal, and counter[1] is not between 1 and 3
# this is the initialized value
counter = 0;
}
}

I’ve also included a screenshot because when I save this answer it may not retain the indentations, making it difficult to read the nested if statement above.