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Hi Zeek --
The for loop indexed by i steps through each bar, starting at the oldest and going through the newest or most recent.
Within that loop, write whatever code you need to compute whatever you want to know about each bar.
The example you have written uses a for loop indexed by j to reference each bar from the first bar newer than the ith bar to the most recent data. Without knowing what it is you want to accomplish, I cannot tell you whether that loop construction is correct or not.
But, it is more common for the bars at and older than the ith bar to be the ones referenced. That is, the j variable will computed so that every bar referenced is older than i. Something like this:
for (j=0;j<5;j++)
{
k = i-j;
something = c[k];
}
When you do this, start the i loop far enough into the data so that k is never less than 0.
Something like this:
for (i=5; i<BarCount; i++)
{
for (j=0;j<5;j++)
{
k = i-j;
something = c[k];
}
}
--------
Finally -- use a variable rather than the number 5. Something like this:
lookback = 5;
for (i=lookback; i<BarCount; i++)
{
for (j=0;j<lookback;j++)
{
k = i-j;
something = c[k];
}
}
The way this example is written, it looks into the future. That might be valuable if you are investigating something, but it cannot be done in real time because we cannot know tomorrow's data.
----------
The statement i = j; is an assignment statement -- not a test of equality.
It assigns to the variable i the value currently stored in the variable j.
In this case, it is poor programming practice, since i is the index variable of a for loop. Better practice is to allow the for loop to control the i variable itself, and not change it within the loop. Depending on the compiler, the results of changing the value of the index variable within the loop may give you exactly what you want (whatever that is), or it may cause abnormal results.
The short advice is -- don't do that.
-------------
Thanks,
Howard
On Mon, May 11, 2009 at 5:58 AM, zeek ing <zeeking57@xxxxxxxxx> wrote:
Hello all
I am trying to understand loops more clearly. I have a question on some code that i have been studying maybe someone can help:
If I have a loop
for( i = 0; i < BarCount; i++ )
{
condition .....
{
for (j = i + 1; j < BarCount; j++)
{ ........ .....
i = j;
break;
}
}
I am trying to understand this loop construct.
a) why would i set J to i+1? why not have j=i?
b) what does i=j accomplish??
if anyone can clarify that would be great, I have seen this loop construct a few times b4.
thanks
zeek
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