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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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IEEE80211_GET_BUFFER(9) 				     Advanced driver interface					   IEEE80211_GET_BUFFER(9)

NAME
ieee80211_get_buffered_bc - accessing buffered broadcast and multicast frames SYNOPSIS
struct sk_buff * ieee80211_get_buffered_bc(struct ieee80211_hw * hw, struct ieee80211_vif * vif); ARGUMENTS
hw pointer as obtained from ieee80211_alloc_hw. vif struct ieee80211_vif pointer from the add_interface callback. DESCRIPTION
Function for accessing buffered broadcast and multicast frames. If hardware/firmware does not implement buffering of broadcast/multicast frames when power saving is used, 802.11 code buffers them in the host memory. The low-level driver uses this function to fetch next buffered frame. In most cases, this is used when generating beacon frame. RETURN
A pointer to the next buffered skb or NULL if no more buffered frames are available. NOTE
buffered frames are returned only after DTIM beacon frame was generated with ieee80211_beacon_get and the low-level driver must thus call ieee80211_beacon_get first. ieee80211_get_buffered_bc returns NULL if the previous generated beacon was not DTIM, so the low-level driver does not need to check for DTIM beacons separately and should be able to use common code for all beacons. AUTHOR
Johannes Berg <johannes@sipsolutions.net> Author. COPYRIGHT
Kernel Hackers Manual 3.10 June 2014 IEEE80211_GET_BUFFER(9)
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