An array question.

[Guest_imported]

howdy,

-I am declaring an array with 100 index.->Data[100];
-Then I initialize all to zero.
-like below.
for(int count;count<100;count++)
Data[count]=0;

-Next Im going to use only 20 index space in the array Data[100]; And the rest of the value would be zero sinc I intitialize to zero.

***My question to you experts is, is there a function or
an easy way to have C++ count how many index are use.
For example we know I only use 20 index space.So it there
is a way then C++ will say,&quot;Oh you use 20 index space&quot;.
I hope you can understand my question.And thanks in advance.

 

[Guest_imported]

Can't think of a predefined function, but there's an easier way to initialize.
Check out ZeroMemory, and FillMemory .

I would just use a member variable to hold the current position.

A little more overhead:
You could use one of the CArray type classes, then you have all the methods associated with them, like:
CArray GetSize(), GetUpperBound().

 

[Zyrenthian]

memset would be another option to set the memory. as for checking and finding the first index that is zero, a simple function adapted from bsearch could be used.

int getLastIndex(int* ptr, int numberOfElements)
{
int done = 0;
int index = numberOfElements/2;
while(!done)
{
if( *(ptr +index) )
index += (numberOfElements-index)/2;
else
index -= (numberOfElements-index)/2;

// double check my logic above

if(!index) return 0;

if(!(*ptr) && *(ptr-1))
return index;
}
}

The idea is there, tho the logic is not yet tested. Hope it helps

Matt

 

[Nosferatu]

An exotic approach that just occured to me would be scanning the contents of the array with a 4 byte pointer and perform logical and's on the memory values found.
Zyrenthian's code above could be slightly changed to take this approach.
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