mem — C Library Procedures

NAME

memchr, memcmp, memcpy, memset − Operations on byte arrays

SYNOPSIS

#include <string.h>
char ∗
memchr(s, c, n)
int
memcmp(s, s2, n)
char ∗
memcpy(dest, source, n)
char ∗
memset(dest, c, n)

ARGUMENTS

char ∗s (in) Pointer to array of characters.

char ∗source (in) Pointer to array of characters to copy.

char ∗dest (out) Pointer to array of characters to modify.

int c (in) Value to search for (memchr), or value to set to (memset).

int n (in) Count of number of characters to test, copy, or set.

DESCRIPTION

These procedures manipulate memory as counted arrays of bytes.

The memchr procedure searches for the first occurrence of c in the n bytes starting at s, and returns the address of the first such occurrence. If the value c is not found, then NULL is returned.

Memcmp compares two arrays of bytes, s and s2, in order, until a difference is found or n bytes have been compared. It returns a value greater than zero if, in the first differing byte, the value s is greater than the value in s2. If the value in s is less than the value in s2, then a value less than zero is returned. If the two arrays are identical in their first n bytes, then zero is returned. Signed character comparison is used.

Memcpy copies n bytes from source to dest and returns dest as its result.

Memset stores the value c in each of the n bytes starting at dest, and returns dest as its result.

KEYWORDS

characters, copy, memory, set, test