C String Functions - C memchr

Copies a character into memory.

void *memchr(const void *str , int c , size_t n );

Searches for the first occurrence of the character c (an unsigned char) in the first n bytes of the string str.

Returns a pointer pointing to the first matching character, or null if no match was found.

Prototype

const void * memchr ( const void * ptr, int value, size_t num );
      void * memchr (       void * ptr, int value, size_t num );

Parameter

This function has the following parameter.

ptr: Pointer to the block of memory where the search is performed.
value: Value to be located.
num: Number of bytes to be analyzed.

size_t is an unsigned integral type.

Return

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 a null pointer.

Example


#include <stdio.h>
#include <string.h>
//  ww w  . j  av a 2s.c o m
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;
}

The code above generates the following result.

Example 2


#include <stdio.h>
#include <string.h>
 /*from   w  w w  .  j a  v  a 2  s. c o  m*/
int main(void){
    char str[] = "ABCDEFG";
    char *ps = memchr(str,'D',strlen(str));
    if (ps != NULL)
       printf ("search character found:  %s\n", ps);
    else
       printf ("search character not found\n");
 
    return 0;
}

The code above generates the following result.