How to empty a buffer, or at least restrict its length

I am writing a multi time frame indicator which shows dots placed in a line in a separate window. I want to restrict the number of dots to 3 ( for displaying a 15 min bars on a 5 min chart)

The relevant section of code I am using is this.

int start()
{
int i,limit;


limit = (TimeFrame1/Period())-1;
for (i=limit; i>= 0; i--)

etc etc

However, what happens is that after another 5 min passes, the number of bars now goes up to 4, and increases after each 5 mins.
What is the process for restricting the number of bars to the original 3?

you didn't post your codes so I can only assume your naming conventions.

assuming you named your buffer as buffer1[]
and assuming you did not change the buffer's empty value to something else.

all you have to do is add the following line to the end of your start function.
that way it constantly have only buffer1[0], buffer1[1] and buffer1[2] having values.

think about it. when a new candle is opened, buffer1[2] will become buffer1[3] and the above stated code will give it a value of nothing thereby removing the square since it has "expired".

to be even more robust, you can have '3' as a configurable value by adding another extern variable.
and at the end of your start function, use the following code
hope this helps.

regards,
Zen

Hi Zen,
Thanks for coming back to me. I am gradually teaching myself MT4 programming, mainly by asking myself questions, and then trying to formulate the answer in code. Moving forward by a process of trial and error.

A little more information. I have adapted a MACD_CCI multi time frame indicator to show me TRIX phases. This mimics a multi colour macd histogram, with buffers containing values for positive and rising, positive and falling, negative and rising and negative and falling.

So far so good. It is the nature of multi time frame indicators that the last bar on the higher time frame always repaints on the lower time frame until the higher time frame bar is closed. This is understood. So I now want to alter the buffer mapping so that the arrow buffers show a "bar in progress" and then, once the higher time frame bar is complete, and the chart moves forward, the completed bars are shown by the squares. (The change from positive to negative is shown by the colour change anyway, so I am only currently duplicating that with arrows.)

And this is where I am stuck. Can you get me any further? As a picture says more than a thousand words (allegedly) I have done a little Photoshop job to show what I mean.


Edit added later:
All fixed now. The answer came to me in a flash while I was doing something completely different. Funny old world...