C- trying to code a 'spare array'; 'enum' fauled. Post: 302697905

Sponsored Content

Top Forums Programming C- trying to code a 'spare array'; 'enum' fauled. Post 302697905 by Corona688 on Friday 7th of September 2012 02:35:44 PM

09-07-2012

Registered User

I have no idea what you're even trying to do with that enum. Usually you'd make an enum like enum { TITLE1=3, TITLE2=5, TITLE3=99 }; so that when you use TITLE1 in your code it becomes the number 3, and so forth. Their values are fixed at compile time, just like a #define and such.

I think you mean 'sparse array', not 'spare array'.

The C language's features closely match the CPU's features, so complex data types like sparse arrays aren't directly supported. You can make them, though. Here's a quick-and-simple one which works as a simple list like you wanted. Not the most efficient if you want it to hold thousands of numbers, but for a few dozen, should be fine...

Code:

#include <stdio.h>
#include <stdlib.h>

typedef struct pair {        int key, value;    } pair;

typedef struct sparse {
        int size, pos;
        pair *p;
}  sparse;

void sparse_free(sparse *s);
sparse *sparse_create(void);
int sparse_get(sparse *s, int key);
int sparse_set(sparse *s, int key, int value);

int main(void)
{
        int n;
        sparse *s=sparse_create();

        // Add a bunch of random elements to the sparse array
        // Keys will be numbers 0 through 7.  Values will be 0 through 10.
        for(n=0; n<10; n++)     sparse_set(s,rand()%8, n);
        // Find everything that was set.  Absent items will show as -1
        for(n=0; n<8; n++)      printf("key %d value %d\n", n, sparse_get(s, n));

        // Print the literal contents of the array raw
        printf("\nContents of sparse array\n");
        for(n=0; n<s->pos; n++)
                printf("I %d\tK %d\tV %d\n", n, s->p[n].key, s->p[n].value);

        sparse_free(s);
        return(0);
}

sparse *sparse_create(void)
{
        sparse *s=malloc(sizeof(sparse));
        if(s == NULL) return(NULL);

        s->size=16;     s->pos=0;
        s->p=malloc(sizeof(pair)*16);
        return(s);
}

int sparse_get(sparse *s, int key)
{
        int n;
        for(n=0; n<s->pos; n++) if(s->p[n].key == key) return(s->p[n].value);

        return(-1);
}

int sparse_set(sparse *s, int key, int value)
{
        int n;

        // Hunt for key.  If found, just update and return.
        for(n=0; n<s->pos; n++)
        if(s->p[n].key == key)
        {
                s->p[n].value=value;
                return(0);
        }

        // Add 16 more elements if full
        if(s->pos >= (s->size - 1))
        {
                pair *p=realloc(s->p, sizeof(pair) * (s->size+16));
                if(p == NULL) return(-1);
                s->size += 16;
                s->p=p;
        }

        // Add to end.
        s->pos++;
        s->p[s->pos].key=key;
        s->p[s->pos].value=value;
        return(0);
}

void sparse_free(sparse *s){ if(s) { free(s->p); free(s); } }

Code:

$ gcc sparse.c
$ ./a.out

key 0 value 0
key 1 value 8
key 2 value 6
key 3 value 3
key 4 value 7
key 5 value -1
key 6 value 1
key 7 value 5

Contents of sparse array
I 0     K 0     V 0
I 1     K 7     V 5
I 2     K 6     V 1
I 3     K 1     V 8
I 4     K 3     V 3
I 5     K 2     V 6
I 6     K 4     V 7

$

Last edited by Corona688; 09-07-2012 at 03:44 PM..

Corona688

View Public Profile for Corona688

Visit Corona688's homepage!

Find all posts by Corona688

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

Vfstab on spare disk - HOW ? Mount ?

Hi, guys ! Could someone clarify one thing for me: I start machine from disk0, and want to check the /etc/vfstab on disk1. How do i do it ? Tried to write: cd / mount /dev/dsk/c0t1d0s0 /mnt But if I do cd /mnt, it is empty. I expected to see disk1 there ? Or am I wrong ? How do I...

2. Programming

what is the base type of enum

helo i have asked in exam what that what is the base type of enum options are given bewlo (1) long int (2) short int (3) signed int (4) unsigned int can u tell me what is the exact answer from the above option Regards, Amit

3. IP Networking

DNS ENUM RR interpretation

Hi Guys, This is really really urgent. Am looking out for some quick answers. I'm developing a DNS Resolver client that interprets DNS Query repsonses & pass on the needful to DNS applications. When an ENUM query(modified to an nslookup naptr query) is issued & an NAPTR RR(Resource Record)...

4. Programming

enum in c++

#include <iostream> #include <stdio.h> using namespace std; typedef struct A { enum a{ red,blue,green}a; }obj11; obj11 obj1; int main() { //obj1.a=red; // how to set variable ? cout<<"sizeof struct is n"<<sizeof(obj1); cout<<"obj1.a is"<<obj1.a; if...

5. Solaris

Hot Spare pool

One more query in SVM :) Now with hot spare spool... I can understand adding/replacing a slice in particular hot spare pool with "-a / -r" option (or) adding a slice to all existing hot spare pool with "-all" option. Here my query is for deleting, we have only option "-d". 1) If the hot...

6. Solaris

Hot Spare replacement

Hi Guys, Can Someone pls let me know the thorough process for Hot spare replacement as current Hot spare slice has broken down . :mad: Thanks ---------- Post updated at 06:34 PM ---------- Previous update was at 05:21 PM ---------- Update : Its a solaris 10 box

7. Programming

enum and C preprocessor

Say I have a list of enumerations I wish to use to select a variable at compile-time: enum pins { PIN_A=1, PIN_B=7, PIN_C=6, } int VAR1, VAR2, VAR3, VAR4, VAR5, VAR6, VAR7; #define PIN_TO_VAR(NUM) VAR ## NUM int main(void) { PIN_TO_VAR(PIN_A)=32;...

8. Solaris

How to get spare disks working

Dears how can i make this spare disks working online to replace a defective disks vxdisk list DEVICE TYPE DISK GROUP STATUS c0t10d0s2 sliced - - error c0t11d0s2 sliced disk08 rootdg online c1t16d0s2 sliced ...

9. Programming

Mixed enum types - coverity defect

Hi All, I came across this error "MIXING ENUM TYPES" when I run my C program against the Coverity Tool. I've made many search relating to the error, but I didnt find the exact solution. Can anyone help me to overcome this.? Thanks in Advance.!!

10. Solaris

How to determine if i have spare disks in Solaris?

Hi Guys, obviously new to SOLARIS SUN SPARC 5.10 I would really appreciate if you help me see how to find free disks available in my system. Like i am a linux admin. If i want to grow a file system in linux. I would first have a look at my volume groups to see if they have free PEs if not then...

LEARN ABOUT X11R4

xkbkeynumactions

XkbKeyNumActions(3)						   XKB FUNCTIONS					       XkbKeyNumActions(3)

NAME

       XkbKeyNumActions - Computes the number of actions associated with the key corresponding to keycode

SYNOPSIS

       int XkbKeyNumActions macro ( xkb, keycode )
	     XkbDescPtr xkb;
	     KeyCode keycode;

ARGUMENTS

       - xkb  Xkb description of interest

       - keycode
	      keycode of interest

DESCRIPTION

       A  key  action  defines	the effect key presses and releases have on the internal state of the server. For example, the expected key action
       associated with pressing the Shift key is to set the Shift modifier. There is zero or one key action associated with each keysym  bound	to
       each key.

       Just as the entire list of key symbols for the keyboard mapping is held in the syms field of the client map, the entire list of key actions
       for the keyboard mapping is held in the acts array of the server map. The total size of acts is specified by size_acts, and the	number	of
       entries is specified by num_acts.

       The  key_acts array, indexed by keycode, describes the actions associated with a key. The key_acts array has min_key_code unused entries at
       the start to allow direct indexing using a keycode. If a key_acts entry is zero, it means the key does not have any actions associated with
       it.  If	an  entry  is  not  zero,  the	entry  represents  an  index  into the acts field of the server map, much as the offset field of a
       KeySymMapRec structure is an index into the syms field of the client map.

       The reason the acts field is a linear list of XkbActions is to reduce the memory consumption associated with a keymap. Because  Xkb  allows
       individual  keys  to  have  multiple shift levels and a different number of groups per key, a single two-dimensional array of KeySyms would
       potentially be very large and sparse. Instead, Xkb provides a small two-dimensional array of XkbActions for each key. To store all of these
       individual arrays, Xkb concatenates each array together in the acts field of the server map.

       The  key  action  structures  consist  only of fields of type char or unsigned char. This is done to optimize data transfer when the server
       sends bytes over the wire. If the fields are anything but bytes, the server has to sift through all of the actions  and	swap  any  nonbyte
       fields. Because they consist of nothing but bytes, it can just copy them out.

       XkbKeyNumActions  computes  the	number	of actions associated with the key corresponding to keycode.  This should be the same value as the
       result of XkbKeyNumSyms.

STRUCTURES

       The KeySymMapRec structure is defined as follows:

	   #define XkbNumKbdGroups	       4
	   #define XkbMaxKbdGroup	       (XkbNumKbdGroups-1)

	   typedef struct {		       /* map to keysyms for a single keycode */
	       unsigned char	   kt_index[XkbNumKbdGroups];  /* key type index for each group */
	       unsigned char	   group_info; /* # of groups and out of range group handling */
	       unsigned char	   width;      /* max # of shift levels for key */
	       unsigned short	   offset;     /* index to keysym table in syms array */
       } XkbSymMapRec, *XkbSymMapPtr;

SEE ALSO

       XkbKeyNumSyms(3)

X Version 11							   libX11 1.2.1 					       XkbKeyNumActions(3)

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

Vfstab on spare disk - HOW ? Mount ?

Discussion started by: DGoubine

2. Programming

what is the base type of enum

Discussion started by: amitpansuria

3. IP Networking

DNS ENUM RR interpretation

Discussion started by: smanu

4. Programming

enum in c++

Discussion started by: crackthehit007