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author | Thomas Fitzsimmons <fitzsim@redhat.com> | 2002-06-20 19:51:40 +0000 |
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committer | Thomas Fitzsimmons <fitzsim@redhat.com> | 2002-06-20 19:51:40 +0000 |
commit | a7b23a8f11b2e1f2ef333d2ed95d1c972acad12f (patch) | |
tree | 26eb76cc430a851b89de107870b4f6b177311072 /newlib/libc/search/hcreate.3 | |
parent | c25ebbaf55dbef934d85522616d898eef37438e4 (diff) | |
download | cygnal-a7b23a8f11b2e1f2ef333d2ed95d1c972acad12f.tar.gz cygnal-a7b23a8f11b2e1f2ef333d2ed95d1c972acad12f.tar.bz2 cygnal-a7b23a8f11b2e1f2ef333d2ed95d1c972acad12f.zip |
* Makefile.am (LIB_OBJECTLISTS): Add
libc/search/objectlist.awk.in.
* libc/Makefile.am (SUBDIRS): Add search.
(SUBLIBS): Add search/libsearch.la.
* libc/configure.in (AC_OUTPUT): Add search/Makefile.
* libc/search: New directory.
* libc/search/Makefile.am: New file.
* libc/search/extern.h: New file.
* libc/search/hash.c: New file.
* libc/search/hash.h: New file.
* libc/search/hash_bigkey.c: New file.
* libc/search/hash_buf.c: New file.
* libc/search/hash_func.c: New file.
* libc/search/hash_log2.c: New file.
* libc/search/hash_page.c: New file.
* libc/search/hcreate.3: New file.
* libc/search/hcreate.c: New file.
* libc/search/hcreate.c~: New file.
* libc/search/hcreate_r.c: New file.
* libc/search/ndbm.c: New file.
* libc/search/page.h: New file.
* libc/search/tdelete.c: New file.
* libc/search/tdestroy.c: New file.
* libc/search/tfind.c: New file.
* libc/search/tsearch.3: New file.
* libc/search/tsearch.c: New file.
* libc/search/twalk.c: New file.
* libc/include/db.h: New file.
* libc/include/ndbm.h: New file.
* libc/include/search.h: New file.
* libc/include/sys/queue.h: New file.
* libc/include/sys/cdefs.h: New file.
* libc/include/sys/param.h
[__IEEE_LITTLE_ENDIAN,__IEEE_BIG_ENDIAN]: Set BYTE_ORDER to
LITTLE_ENDIAN or BIG_ENDIAN.
* libc/include/sys/errno.h (EFTYPE): New macro.
* libc/search/bsearch.c: Move from libc/stdlib.
* libc/search/qsort.c: Likewise.
* libc/stdlib/Makefile.am (LIB_SOURCES): Remove bsearch.c and
qsort.c.
(CHEWOUT_FILES): Remove bsearch.def and qsort.def.
* libc/stdlib/stdlib.tex: Remove references to bsearch and qsort.
Diffstat (limited to 'newlib/libc/search/hcreate.3')
-rw-r--r-- | newlib/libc/search/hcreate.3 | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/newlib/libc/search/hcreate.3 b/newlib/libc/search/hcreate.3 new file mode 100644 index 000000000..1619c9892 --- /dev/null +++ b/newlib/libc/search/hcreate.3 @@ -0,0 +1,206 @@ +.\" $FreeBSD: src/lib/libc/stdlib/hcreate.3,v 1.2 2001/07/09 15:54:36 ru Exp $ +.\" +.Dd May 8, 2001 +.Os +.Dt HCREATE 3 +.Sh NAME +.Nm hcreate , hdestroy , hsearch +.Nd manage hash search table +.Sh LIBRARY +.Lb libc +.Sh SYNOPSIS +.In search.h +.Ft int +.Fn hcreate "size_t nel" +.Ft void +.Fn hdestroy void +.Ft ENTRY * +.Fn hsearch "ENTRY item" "ACTION action" +.Sh DESCRIPTION +The +.Fn hcreate , +.Fn hdestroy , +and +.Fn hsearch +functions manage hash search tables. +.Pp +The +.Fn hcreate +function allocates sufficient space for the table, and the application should +ensure it is called before +.Fn hsearch +is used. +The +.Fa nel +argument is an estimate of the maximum +number of entries that the table should contain. +This number may be adjusted upward by the +algorithm in order to obtain certain mathematically favorable circumstances. +.Pp +The +.Fn hdestroy +function disposes of the search table, and may be followed by another call to +.Fn hcreate . +After the call to +.Fn hdestroy , +the data can no longer be considered accessible. +.Pp +The +.Fn hsearch +function is a hash-table search routine. +It returns a pointer into a hash table +indicating the location at which an entry can be found. +The +.Fa item +argument is a structure of type +.Vt ENTRY +(defined in the +.Aq Pa search.h +header) containing two pointers: +.Fa item.key +points to the comparison key (a +.Vt "char *" ) , +and +.Fa item.data +(a +.Vt "void *" ) +points to any other data to be associated with +that key. +The comparison function used by +.Fn hsearch +is +.Xr strcmp 3 . +The +.Fa action +argument is a +member of an enumeration type +.Vt ACTION +indicating the disposition of the entry if it cannot be +found in the table. +.Dv ENTER +indicates that the +.Fa item +should be inserted in the table at an +appropriate point. +.Dv FIND +indicates that no entry should be made. +Unsuccessful resolution is +indicated by the return of a +.Dv NULL +pointer. +.Sh RETURN VALUES +The +.Fn hcreate +function returns 0 if it cannot allocate sufficient space for the table; +otherwise, it returns non-zero. +.Pp +The +.Fn hdestroy +function does not return a value. +.Pp +The +.Fn hsearch +function returns a +.Dv NULL +pointer if either the +.Fa action +is +.Dv FIND +and the +.Fa item +could not be found or the +.Fa action +is +.Dv ENTER +and the table is full. +.Sh ERRORS +The +.Fn hcreate +and +.Fn hsearch +functions may fail if: +.Bl -tag -width Er +.It Bq Er ENOMEM +Insufficient storage space is available. +.El +.Sh EXAMPLES +The following example reads in strings followed by two numbers +and stores them in a hash table, discarding duplicates. +It then reads in strings and finds the matching entry in the hash +table and prints it out. +.Bd -literal +#include <stdio.h> +#include <search.h> +#include <string.h> + +struct info { /* This is the info stored in the table */ + int age, room; /* other than the key. */ +}; + +#define NUM_EMPL 5000 /* # of elements in search table. */ + +int +main(void) +{ + char string_space[NUM_EMPL*20]; /* Space to store strings. */ + struct info info_space[NUM_EMPL]; /* Space to store employee info. */ + char *str_ptr = string_space; /* Next space in string_space. */ + struct info *info_ptr = info_space; /* Next space in info_space. */ + ENTRY item; + ENTRY *found_item; /* Name to look for in table. */ + char name_to_find[30]; + int i = 0; + + /* Create table; no error checking is performed. */ + (void) hcreate(NUM_EMPL); + + while (scanf("%s%d%d", str_ptr, &info_ptr->age, + &info_ptr->room) != EOF && i++ < NUM_EMPL) { + /* Put information in structure, and structure in item. */ + item.key = str_ptr; + item.data = info_ptr; + str_ptr += strlen(str_ptr) + 1; + info_ptr++; + /* Put item into table. */ + (void) hsearch(item, ENTER); + } + + /* Access table. */ + item.key = name_to_find; + while (scanf("%s", item.key) != EOF) { + if ((found_item = hsearch(item, FIND)) != NULL) { + /* If item is in the table. */ + (void)printf("found %s, age = %d, room = %d\en", + found_item->key, + ((struct info *)found_item->data)->age, + ((struct info *)found_item->data)->room); + } else + (void)printf("no such employee %s\en", name_to_find); + } + return 0; +} +.Ed +.Sh SEE ALSO +.Xr bsearch 3 , +.Xr lsearch 3 , +.Xr malloc 3 , +.Xr strcmp 3 , +.Xr tsearch 3 +.Sh STANDARDS +The +.Fn hcreate , +.Fn hdestroy , +and +.Fn hsearch +functions conform to +.St -xpg4.2 . +.Sh HISTORY +The +.Fn hcreate , +.Fn hdestroy , +and +.Fn hsearch +functions first appeared in +.At V . +.Sh BUGS +The interface permits the use of only one hash table at a time. |