memchr
From cppreference.com
Defined in header <string.h>
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void
* memchr(
const
void
* ptr, int ch, size_t count )
;
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(1) | |
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/*QVoid*/
*memchr(
/*QVoid*/
*ptr, int ch, size_t count )
;
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(2) | (since C23) |
1) Finds the first occurrence of (unsigned char)ch in the initial count bytes (each interpreted as unsigned char) of the object pointed to by ptr
2) Type-generic function equivalent to (1). Let
T be an 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
The behavior is undefined if access occurs beyond the end of the array searched. The behavior is undefined if ptr is a null pointer.
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This function behaves as if it reads the bytes sequentially and stops as soon as a matching bytes is found: if the array pointed to by ptr is smaller than count |
(since C11) |
Parameters
| ptr | - | pointer to the object to be examined |
| ch | - | bytes to search for |
| count | - | max number of bytes to examine |
Return value
Pointer to the location of the byte, or a null pointer if no such byte is found.
Example
Run this code
#include <stdio.h> #include <string.h> int main(void) { const char str[] = "ABCDEFG"; const int chars[] = {'D', 'd'}; for (size_t i = 0; i < sizeof chars / (sizeof chars[0]); ++i) { const int c = chars[i]; const char *ps = memchr(str, c, strlen(str)); ps ? printf ("character '%c'(%i) found: %s\n", c, c, ps) : printf ("character '%c'(%i) not found\n", c, c); } return 0; }
Possible output:
character 'D'(68) found: DEFG character 'd'(100) not found
References
- C23 standard (ISO/IEC 9899:2024):
- 7.24.5.1 The memchr function (p: TBD)
- C17 standard (ISO/IEC 9899:2018):
- 7.24.5.1 The memchr function (p: 267-268)
- C11 standard (ISO/IEC 9899:2011):
- 7.24.5.1 The memchr function (p: 367)
- C99 standard (ISO/IEC 9899:1999):
- 7.21.5.1 The memchr function (p: 330)
- C89/C90 standard (ISO/IEC 9899:1990):
- 4.11.5.1 The memchr function
See also
| finds the first occurrence of a character (function) |
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C++ documentation for memchr
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