| | 1 | .\" Copyright (c) 1990, 1991, 1993, 1994 |
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| | 4 | .\" This code is derived from software contributed to Berkeley by |
| | 5 | .\" the American National Standards Committee X3, on Information |
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| | 20 | .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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| | 32 | .\" @(#)bsearch.3 8.3 (Berkeley) 4/19/94 |
| | 33 | .\" $FreeBSD: src/lib/libc/stdlib/bsearch.3,v 1.9 2007/01/09 00:28:09 imp Exp $ |
| | 34 | .\" |
| | 35 | .Dd May 20, 2008 |
| | 36 | .Dt BSEARCH 3 |
| | 37 | .Os |
| | 38 | .Sh NAME |
| | 39 | #ifdef UNIFDEF_BLOCKS |
| | 40 | .Nm bsearch , |
| | 41 | .Nm bsearch_b |
| | 42 | #else |
| | 43 | .Nm bsearch |
| | 44 | #endif |
| | 45 | .Nd binary search of a sorted table |
| | 46 | .Sh SYNOPSIS |
| | 47 | .In stdlib.h |
| | 48 | .Ft void * |
| | 49 | .Fn bsearch "const void *key" "const void *base" "size_t nel" "size_t width" "int (*compar) (const void *, const void *)" |
| | 50 | #ifdef UNIFDEF_BLOCKS |
| | 51 | .Ft void * |
| | 52 | .Fn bsearch_b "const void *key" "const void *base" "size_t nel" "size_t width" "int (^compar) (const void *, const void *)" |
| | 53 | #endif |
| | 54 | .Sh DESCRIPTION |
| | 55 | The |
| | 56 | .Fn bsearch |
| | 57 | function searches an array of |
| | 58 | .Fa nel |
| | 59 | objects, the initial member of which is |
| | 60 | pointed to by |
| | 61 | .Fa base , |
| | 62 | for a member that matches the object pointed to by |
| | 63 | .Fa key . |
| | 64 | The size (in bytes) of each member of the array is specified by |
| | 65 | .Fa width . |
| | 66 | .Pp |
| | 67 | The contents of the array should be in ascending sorted order according |
| | 68 | to the comparison function referenced by |
| | 69 | .Fa compar . |
| | 70 | The |
| | 71 | .Fa compar |
| | 72 | routine |
| | 73 | is expected to have |
| | 74 | two arguments which point to the |
| | 75 | .Fa key |
| | 76 | object and to an array member, in that order. |
| | 77 | It should return an integer which is |
| | 78 | less than, equal to, or greater than zero if the |
| | 79 | .Fa key |
| | 80 | object is found, respectively, to be less than, to match, or be |
| | 81 | greater than the array member. |
| | 82 | #ifdef UNIFDEF_BLOCKS |
| | 83 | .Pp |
| | 84 | The |
| | 85 | .Fn bsearch_b |
| | 86 | function is like |
| | 87 | .Fn bsearch |
| | 88 | except the callback |
| | 89 | .Fa compar |
| | 90 | is a block pointer instead of a function pointer. |
| | 91 | #endif |
| | 92 | .Sh RETURN VALUES |
| | 93 | The |
| | 94 | .Fn bsearch |
| | 95 | #ifdef UNIFDEF_BLOCKS |
| | 96 | and |
| | 97 | .Fn bsearch_b |
| | 98 | functions |
| | 99 | #else |
| | 100 | function |
| | 101 | #endif |
| | 102 | returns a pointer to a matching member of the array, or a null |
| | 103 | pointer if no match is found. |
| | 104 | If two members compare as equal, which member is matched is unspecified. |
| | 105 | .Sh SEE ALSO |
| | 106 | .Xr db 3 , |
| | 107 | .Xr lsearch 3 , |
| | 108 | .Xr qsort 3 |
| | 109 | .\" .Xr tsearch 3 |
| | 110 | .Sh STANDARDS |
| | 111 | The |
| | 112 | .Fn bsearch |
| | 113 | function conforms to |
| | 114 | .St -isoC . |
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