Pointers -to the start and end of contiguous regions

For those arrays of same length elements which are derived from CArrayFix<class T>, -the elements are contained within an array buffer which can be implemented -as a flat buffer or as a segmented buffer. A flat buffer is implemented as -a single contiguous region of memory while a segmented buffer is implemented -as a set of separate but linked regions of memory

Given the position of an element within an array, it can be useful to fetch -a pointer to the first byte following the end of the contiguous region of -memory containing that element (the end pointer). Similarly, it can -be useful to fetch a pointer to the beginning of a contiguous region -of memory (the back pointer).

Array of same length elements

An array of same -length elements uses the End() function to fetch the end -pointer and the Back() function to fetch the back pointer. -The implementation of these two functions differs between a fixed flat array -and a fixed segmented array.

Flat array

For a flat array — i.e. an array whose -buffer is implemented using a flat buffer — the end pointer simply points -to the first byte following the single region of memory containing the array -buffer. The back pointer simply points to the first byte of the single region -of memory (as illustrated below); End() always returns a -pointer to the first byte following the end of the buffer, while Back() always -returns a pointer to the beginning of the buffer.

-End() and Back() in fixed flat arrays - -

Segmented array

For a segmented array, the situation -is different (as illustrated below). Looking at the segment containing elements n and n+1, End() returns a pointer to the first byte following the end of that segment. In -fact, End() returns the same pointer value for all elements -in that segment. Back() returns a pointer to the beginning -of that segment for element n+1 and for all subsequent elements -in that segment. However, for the first element in that segment, Back() returns -a pointer to the beginning of the previous segment. For the very first -element in the array, Back() returns a pointer with a NULL -value.

-End() and Back() in fixed segmented arrays - -

See also

Dynamic -Buffers Guide.

+ + + + + +Pointers +to the start and end of contiguous regionsThe Back() and End() functions +point to locations in memory for flat and segmented arrays. +

For those arrays of same length elements which are derived from CArrayFix<class T>, +the elements are contained within an array buffer which can be implemented +as a flat buffer or as a segmented buffer. A flat buffer is implemented as +a single contiguous region of memory while a segmented buffer is implemented +as a set of separate but linked regions of memory

Given the position of an element within an array, it can be useful to fetch +a pointer to the first byte following the end of the contiguous region of +memory containing that element (the end pointer). Similarly, it can +be useful to fetch a pointer to the beginning of a contiguous region +of memory (the back pointer).

Array of same length elements

An array of same +length elements uses the End() function to fetch the end +pointer and the Back() function to fetch the back pointer. +The implementation of these two functions differs between a fixed flat array +and a fixed segmented array.

Flat array

For a flat array — i.e. an array whose +buffer is implemented using a flat buffer — the end pointer simply points +to the first byte following the single region of memory containing the array +buffer. The back pointer simply points to the first byte of the single region +of memory (as illustrated below); End() always returns a +pointer to the first byte following the end of the buffer, while Back() always +returns a pointer to the beginning of the buffer.

+End() and Back() in fixed flat arrays + +

Segmented array

For a segmented array, the situation +is different (as illustrated below). Looking at the segment containing elements n and n+1, End() returns a pointer to the first byte following the end of that segment. In +fact, End() returns the same pointer value for all elements +in that segment. Back() returns a pointer to the beginning +of that segment for element n+1 and for all subsequent elements +in that segment. However, for the first element in that segment, Back() returns +a pointer to the beginning of the previous segment. For the very first +element in the array, Back() returns a pointer with a NULL +value.

+End() and Back() in fixed segmented arrays + +