memchr
From cppreference.com
C
Concurrency support (C11)
Null-terminated byte strings
Functions
Character manipulation
Conversions to and from numeric formats
(C99)(C99)
(C99)(C99)
(C23)(C23)(C23)
String manipulation
String examination
Memory manipulation
Miscellaneous
(C11)(C11)
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)[edit] Parameters
ptr
-
pointer to the object to be examined
ch
-
bytes to search for
count
-
max number of bytes to examine
[edit] Return value
Pointer to the location of the byte, or a null pointer if no such byte is found.
[edit] 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
[edit] 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
[edit] See also
C++ documentation for memchr