memchr

C

Language

Headers

Type support

Program utilities

Variadic function support

Error handling

Dynamic memory management

Date and time utilities

Strings library

Algorithms

Numerics

Input/output support

Localization support

Atomic operations (C11)

Thread support (C11)

Technical Specifications

Strings library

Byte strings

Multibyte strings

Wide strings

Null-terminated byte strings

Functions
Character manipulation
isalnum isalpha islower isupper isdigit isxdigit isblank (C99)	iscntrl isgraph isspace isprint ispunct tolower toupper
Conversions to numeric formats
atof atoiatolatoll (C99) strtolstrtoll (C99)	strtoulstrtoull (C99) strtofstrtodstrtold (C99)(C99) strtoimaxstrtoumax (C99)(C99)
String manipulation
strcpystrcpy_s (C11)
strncpystrncpy_s (C11)
strcatstrcat_s (C11)
strncatstrncat_s (C11)
strxfrm
String examination
strlenstrnlen_s (C11) strcmp strncmp strcoll strchr strrchr	strspn strcspn strpbrk strstr strtokstrtok_s (C11)
Memory manipulation
memchr
memcmp
memsetmemset_s (C11)
memcpymemcpy_s (C11)
memmovememmove_s (C11)
Miscellaneous
strerrorstrerror_sstrerrorlen_s (C11)(C11)

Defined in header <string.h>
void* memchr( const void* ptr, int ch, size_t count );

Finds the first occurrence of ch (after conversion to unsigned char as if by (unsigned char)ch) in the initial count characters (each interpreted as unsigned char) of the object pointed to by ptr.

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 characters sequentially and stops as soon as a matching character 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)

Parameters

ptr	-	pointer to the object to be examined
ch	-	character to search for
count	-	max number of characters to examine

Return value

Pointer to the location of the character, or NULL if no such character is found.

Example

Run this code

#include <stdio.h>
#include <string.h>

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;
}

Output:

search character found:  DEFG

References

• 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

See also

strchr

finds the first occurrence of a character (function)