memchr
From cppreference.com
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Defined in header
<string.h>
|
||
|
void
*
memchr
(
const
void
*
ptr,
int
ch,
size_t
count
)
;
|
(1) | |
|
/*QVoid*/
*
memchr
(
/*QVoid*/
*
ptr,
int
ch,
size_t
count
)
;
|
(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.
|
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 , but the match is found within the array, the behavior is well-defined. |
(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) |
|
|
C++ documentation
for
memchr
|
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