<cstring>
const void * memchr ( const void * ptr, int value, size_t num );
void * memchr ( void * ptr, int value, size_t num );
Locate character in block of memory
Searches within the first num bytes of the block of memory pointed by ptr for the first occurrence of value (interpreted as an unsigned char), and returns a pointer to it.
Parameters
- ptr
- Pointer to the block of memory where the search is performed.
- value
- Value to be located. The value is passed as an int, but the function performs a byte per byte search using the unsigned char conversion of this value.
- num
- Number of bytes to be analyzed.
Return Value
A pointer to the first occurrence of value in the block of memory pointed by ptr.
If the value is not found, the function returns NULL.
Portability
In C, this function is declared as:
void * memchr ( const void *, int, size_t );
instead of the two overloaded versions provided in C++.
Example
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
|
/* memchr example */
#include <stdio.h>
#include <string.h>
int main ()
{
char * pch;
char str[] = "Example string";
pch = (char*) memchr (str, 'p', strlen(str));
if (pch!=NULL)
printf ("'p' found at position %d.\n", pch-str+1);
else
printf ("'p' not found.\n");
return 0;
}
|
Output:
See also
| memcmp | Compare two blocks of memory (function) |
| strchr | Locate first occurrence of character in string (function) |
| strrchr | Locate last occurrence of character in string (function) |
|