memchr

memchr

Locate First Occurrence of a Character

Portability: ISO/ANSI C conforming, UNIX compatible

SYNOPSIS
DESCRIPTION
RETURN VALUE
CAUTION
EXAMPLE
RELATED FUNCTIONS
SEE ALSO

SYNOPSIS

#include <string.h>

void *memchr(const void *ptr, int ch, size_t n);

DESCRIPTION

memchr searches n bytes, beginning at the location pointed to by ptr , for the first occurrence of ch .

RETURN VALUE

The return value is a pointer to the first occurence of ch , or NULL if the character cannot be found.

CAUTION

The third argument to memchr is size_t .

See the description section for memscntb for information on possible interactions between the memchr , memscntb , or strscntb functions.

EXAMPLE

This example counts the number of zero bytes in a 256-byte memory area:

#include <string.h>
#include <stdio.h>
#define SIZE 256

main()
{
   char area[SIZE];
   int offset = 0;
   int count = 0;
   char *next, *prev;
   int i;

      /* Every alternate element is assigned zero value. */
   for (i = 0; i <= 255; i+=2) {
      area[i] = '\1';
      area[i+1] = '\0';
   }
   prev = area;
   for (;;) {
      next = memchr(prev, '\0' , 256 - offset);
      if (!next) break;
      ++count;
      prev = next+1;
      offset = (prev - area + 1);
   }
   printf("%d zero bytes found. \n", count);
}

RELATED FUNCTIONS

strchr , memscan

SEE ALSO

String Utility Functions

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