memchr, wmemchr
The new home for Visual Studio documentation is Visual Studio 2017 Documentation on docs.microsoft.com.
The latest version of this topic can be found at memchr, wmemchr.
Find characters in a buffer.
void *memchr( const void *buf, int c, size_t count ); // C only void *memchr( void *buf, int c, size_t count ); // C++ only const void *memchr( const void *buf, int c, size_t count ); // C++ only wchar_t *wmemchr( const wchar_t * buf, wchar_t c, size_t count ); // C only wchar_t *wmemchr( wchar_t * buf, wchar_t c, size_t count ); // C++ only const wchar_t *wmemchr( const wchar_t * buf, wchar_t c, size_t count ); // C++ only
Parameters
buf
Pointer to buffer.
c
Character to look for.
count
Number of characters to check.
If successful, returns a pointer to the first location of c in buf. Otherwise it returns NULL.
memchr and wmemchr look for the first occurrence of c in the first count bytes of buf. It stops when it finds c or when it has checked the first count bytes.
In C, these functions take a const pointer for the first argument. In C++, two overloads are available. The overload taking a pointer to const returns a pointer to const; the version that takes a pointer to non-const returns a pointer to non-const. The macro _CONST_CORRECT_OVERLOADS is defined if both the const and non-const versions of these functions are available. If you require the non-const behavior for both C++ overloadsin C++, define the symbol _CONST_RETURN.
| Routine | Required header |
|---|---|
memchr | <memory.h> or <string.h> |
wmemchr | <wchar.h> |
For more information about compatibility, see Compatibility.
All versions of the C run-time libraries.
// crt_memchr.c
#include <memory.h>
#include <stdio.h>
int ch = 'r';
char str[] = "lazy";
char string[] = "The quick brown dog jumps over the lazy fox";
char fmt1[] = " 1 2 3 4 5";
char fmt2[] = "12345678901234567890123456789012345678901234567890";
int main( void )
{
char *pdest;
int result;
printf( "String to be searched:\n %s\n", string );
printf( " %s\n %s\n\n", fmt1, fmt2 );
printf( "Search char: %c\n", ch );
pdest = memchr( string, ch, sizeof( string ) );
result = (int)(pdest - string + 1);
if ( pdest != NULL )
printf( "Result: %c found at position %d\n", ch, result );
else
printf( "Result: %c not found\n" );
}
String to be searched:
The quick brown dog jumps over the lazy fox
1 2 3 4 5
12345678901234567890123456789012345678901234567890
Search char: r
Result: r found at position 12
Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.
Buffer Manipulation
_memccpy
memcmp, wmemcmp
memcpy, wmemcpy
memset, wmemset
strchr, wcschr, _mbschr, _mbschr_l