Enumeration in C language

Question

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I working on low level C functions so i find a lot of code complex . Can someone explain me this piece of code?

if (req.pib_attr == ZB_PHY_PIB_CURRENT_CHANNEL)

zb_mlme_get_request_t req;

CSS

typedef struct zb_mlme_get_request_s
{
  zb_mac_pib_attr_t  pib_attr;
  zb_uint8_t          pib_index;
} ZB_PACKED_STRUCT
zb_mlme_get_request_t;

C#

typedef enum
{
  /* PHY PIB */
  ZB_PHY_PIB_CURRENT_CHANNEL                    = 0x00,
  ZB_PHY_PIB_CURRENT_PAGE                       = 0x04,
  /* MAC PIB */
  ZB_PIB_ATTRIBUTE_ACK_WAIT_DURATION            = 0x40,
  ZB_PIB_ATTRIBUTE_ASSOCIATION_PERMIT           = 0x41,
  ZB_PIB_ATTRIBUTE_AUTO_REQUEST                 = 0x42,
  ZB_PIB_ATTRIBUTE_BATT_LIFE_EXT                = 0x43,
  ZB_PIB_ATTRIBUTE_BATT_LIFE_EXT_PERIODS        = 0x44,
  ZB_PIB_ATTRIBUTE_BEACON_PAYLOAD               = 0x45,
  ZB_PIB_ATTRIBUTE_BEACON_PAYLOAD_LENGTH        = 0x46,
  ZB_PIB_ATTRIBUTE_BEACON_ORDER                 = 0x47,
  ZB_PIB_ATTRIBUTE_BEACON_TX_TIME               = 0x48,
  ZB_PIB_ATTRIBUTE_BSN                          = 0x49,
  ZB_PIB_ATTRIBUTE_COORD_EXTEND_ADDRESS         = 0x4a,
  ZB_PIB_ATTRIBUTE_COORD_SHORT_ADDRESS          = 0x4b,
  ZB_PIB_ATTRIBUTE_DSN                          = 0x4c,
  ZB_PIB_ATTRIBUTE_TIMESTAMP_SUPPORTED          = 0x5c,
  ZB_PIB_ATTRIBUTE_SECURITY_ENABLED             = 0x5d
} zb_mac_pib_attr_t;

Here enum is nested inside a structure .

If condition is checked here total enum variable req.pibattr is checked against a member of enum. I have checked values are not assigned to

req.pib_attr

..

How the condition will be executed .

Posted 26-Dec-12 3:00am

steven8Gerrard

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Comments

Sergey Alexandrovich Kryukov 26-Dec-12 12:43pm

This is not a good question. Why asking about something you did not write?

You are coming to the problem from wrong side. Why reading someone's code is you don't understand it? Learn the language first, write your own code instead, for exercise. When you are done, look at someone's code again. By the way, one simple advice: start from reading the whole manual at once in one single block. Even if you would not understand everything, you will get a good idea on what's involved.
—SA

3 solutions

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Anele Ngqandu · Answer 1 · 2012-12-26T22:44:00

Solution 3

Hi

If you want to learn how enum work in c#, you can check this Example

Posted 26-Dec-12 22:44pm

Anele Ngqandu

Philippe Mori · Answer 2 · 2012-12-26T17:28:00

Solution 2

The comparison will compare the value in the variable req.pib_attr to the value of ZB_PHY_PIB_CURRENT_CHANNEL which is 0...

It is not much different than comparing a variable with a constant.

C++

int a = 5;
if (a == 7) { ... }

Posted 26-Dec-12 17:28pm

Philippe Mori

*Suvabrata Roy* · Answer 3 · 2012-12-26T03:05:00

Solution 1

Hi,

I think this link will help you.

Enum[^]

Posted 26-Dec-12 3:05am

Suvabrata Roy

Comments

steven8Gerrard 26-Dec-12 9:17am

TBH i have knowledge on ENUM and know how it works . I just haven't used enum in work . Here i just wish how if condition checks . Total enum structure will be compared against member of enum.

Andreas Gieriet 28-Dec-12 16:42pm

You seem *not* to know what enum is: an enum is a way to define a set of symbols that each represent a specific integral number. An enum is *not* a struct. Instead of defining an enum type, one could likewise have defined each of its symbols as individual int constants.
Cheers
Andi