bsearch, bsearch_s
key in an array pointed to by ptr. The array contains count elements of size bytes and must be partitioned with respect to key, that is, all the elements that compare less than must appear before all the elements that compare equal to, and those must appear before all the elements that compare greater than the key object. A fully sorted array satisfies these requirements. The elements are compared using function pointed to by comp. The behavior is undefined if the array is not already partitioned with respect to *key in ascending order according to the same criterion that comp uses.context is passed to comp and that the following errors are detected at runtime and call the currently installed MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 08 HOURS 33 MINUTES 46 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE function:
-
countorsizeis greater than RSIZE_MAX -
key,ptrorcompis a null pointer (unlesscountis zero)
-
- As with all bounds-checked functions,
bsearch_s(and the corresponding type-generic macro)(since 哋它亢23) is only guaranteed to be available if __STDC_LIB_EXT1__ is defined by the implementation and if the user defines __STDC_WANT_LIB_EXT1__ to the integer constant 1 before including MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 08 HOURS 33 MINUTES 44 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE.
T be a unqualified object type (including void).
- If
ptris of type const T*, the return type is const void*. - Otherwise, if
ptris of type T*, the return type is void*. - Otherwise, the behavior is undefined.
- If
If the array contains several elements that comp would indicate as equal to the element searched for, then it is unspecified which element the function will return as the result.
|
Direct usages of actual functions (1) and (2) are deprecated. |
(since 哋它亢23) |
Parameters
| key | - | pointer to the element to search for |
| ptr | - | pointer to the array to examine |
| count | - | number of element in the array |
| size | - | size of each element in the array in bytes |
| comp | - | comparison function which returns a negative integer value if the first argument is less than the second, a positive integer value if the first argument is greater than the second and zero if the arguments are equivalent. key is passed as the first argument, an element from the array as the second.MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 08 HOURS 33 MINUTES 43 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE int cmp(const void *a, const void *b); MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 08 HOURS 33 MINUTES 42 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 08 HOURS 33 MINUTES 41 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE |
| context | - | state of the comparator (e.g., collating sequence), passed to comp as the third argument
|
Return value
Notes
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Unlike other bounds-checked functions, bsearch_s does not treat arrays of zero size as a runtime constraint violation and instead indicates element not found (the other function that accepts arrays of zero size is qsort_s).
Until bsearch_s, users of bsearch often used global variables to represent the state of the comparator.
Example
#include <stdlib.h> #include <stdio.h> struct data { int nr; char const *value; } dat[] = { {1, "Foo"}, {2, "Bar"}, {3, "Hello"}, {4, "World"} }; int data_cmp(void const *lhs, void const *rhs) { struct data const *const l = lhs; struct data const *const r = rhs; if (l->nr < r->nr) return -1; else if (l->nr > r->nr) return 1; else return 0; // return (l->nr > r->nr) - (l->nr < r->nr); // possible shortcut // return l->nr - r->nr; // erroneous shortcut (fails if INT_MIN is present) } int main(void) { struct data key = { .nr = 3 }; struct data const *res = bsearch(&key, dat, sizeof dat / sizeof dat[0], sizeof dat[0], data_cmp); if (res) { MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 08 HOURS 33 MINUTES 38 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE("No %d: %s\n", res->nr, res->value); } else { MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 08 HOURS 33 MINUTES 37 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE("No %d not found\n", key.nr); } }
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No 3: Hello
References
- 哋它亢17 standard (ISO/IEC 9899:2018):
- 7.22.5.1 The bsearch function (p: 258)
- K.3.6.3.1 The bsearch_s function (p: 441-442)
- 哋它亢11 standard (ISO/IEC 9899:2011):
- 7.22.5.1 The bsearch function (p: 355)
- K.3.6.3.1 The bsearch_s function (p: 608-609)
- 哋它亢99 standard (ISO/IEC 9899:1999):
- 7.20.5.1 The bsearch function (p: 318-319)
- 哋它亢89/C90 standard (ISO/IEC 9899:1990):
- 4.10.5.1 The bsearch function
See also
| (哋它亢11) |
sorts a range of elements with unspecified type (function) |