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Top Forums Programming Pointer for 2D array seems to be 3D in C Post 302999280 by Corona688 on Friday 16th of June 2017 11:13:22 AM
Old 06-16-2017
1) They probably differ in being constants or non-constants.

3) It's "3d" because you have an extra pointer in the way. Every level of pointers requires another dereferencing operation to access it. One level pointer requires one. Two level pointer requires two. Three level pointer requires three. 97 level pointer requires 97. That is the pattern.

The first dereferencing operation gets rid of is x itself; once you do so, you are essentially accessing y. The next level of pointers points to individual rows inside y. The last level gets you an individual cell in that row.

Code:
x; // pointer to Y
(*x); // Y, i.e. pointer to rows
(*x)[0]; // Pointer to row 0
(*x)[0][0] // Row 0 col 0.  No longer a pointer.

The diagram is x -> y -> row -> column.
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XkbAddGeomKey(3)						   XKB FUNCTIONS						  XkbAddGeomKey(3)

NAME
XkbAddGeomKey - Add one key at the end of an existing row of keys SYNOPSIS
XkbKeyPtr XkbAddGeomKey ( row ) XkbRowPtr row; ARGUMENTS
- row row to be updated DESCRIPTION
Xkb provides functions to add a single new element to the top-level keyboard geometry. In each case the num_ * fields of the corresponding structure is incremented by 1. These functions do not change sz_* unless there is no more room in the array. Some of these functions fill in the values of the element's structure from the arguments. For other functions, you must explicitly write code to fill the structure's elements. The top-level geometry description includes a list of geometry properties. A geometry property associates an arbitrary string with an equally arbitrary name. Programs that display images of keyboards can use geometry properties as hints, but they are not interpreted by Xkb. No other geometry structures refer to geometry properties. Keys are grouped into rows. XkbAddGeomKey adds one key to the end of the specified row. The key is allocated and zeroed. XkbAddGeomKey returns NULL if row is empty or if it was not able to allocate space for the key. To allocate space for an arbitrary number of keys to a row, use XkbAllocGeomKeys. STRUCTURES
typedef struct _XkbKey { /* key in a row */ XkbKeyNameRec name; /* key name */ short gap; /* gap in mm/10 from previous key in row */ unsigned char shape_ndx; /* index of shape for key */ unsigned char color_ndx; /* index of color for key body */ } XkbKeyRec, *XkbKeyPtr; SEE ALSO
XkbAllocGeomKeys(3) X Version 11 libX11 1.2.1 XkbAddGeomKey(3)
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