1memory(3C)               Standard C Library Functions               memory(3C)
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NAME

6       memory, memccpy, memchr, memcmp, memcpy, memmove, memset - memory oper‐
7       ations
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SYNOPSIS

10       #include <string.h>
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12       void *memccpy(void *restrict s1, const void *restrict s2,
13            int c, size_t n);
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16       void *memchr(const void *s, int c, size_t n);
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19       int memcmp(const void *s1, const void *s2, size_t n);
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22       void *memcpy(void *restrict s1, const void *restrict s2, size_t n);
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25       void *memmove(void *s1, const void *s2, size_t n);
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28       void *memset(void *s, int c, size_t n);
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31   ISO C++
32       #include <string.h>
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34       const void *memchr(const void *s, int c, size_t n);
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37       #include <cstring>
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39       void *std::memchr(void *s, int c, size_t n);
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DESCRIPTION

43       These functions operate as efficiently  as  possible  on  memory  areas
44       (arrays  of  bytes bounded by a count, not terminated by a null charac‐
45       ter). They do not check for the overflow of any receiving memory area.
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48       The memccpy() function copies bytes from memory area s2 into s1,  stop‐
49       ping  after  the  first occurrence of c (converted to an unsigned char)
50       has been copied, or after n bytes have  been  copied,  whichever  comes
51       first. It returns a pointer to the byte after the copy of c in s1, or a
52       null pointer if c was not found in the first n bytes of s2.
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55       The memchr() function returns a pointer to the first  occurrence  of  c
56       (converted  to an unsigned char) in the first n bytes (each interpreted
57       as an unsigned char) of memory area s, or a null pointer if c does  not
58       occur.
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61       The  memcmp()  function  compares its arguments, looking at the first n
62       bytes (each interpreted as an unsigned char), and  returns  an  integer
63       less than, equal to, or greater than 0, according as s1 is lexicograph‐
64       ically less than, equal to,  or  greater  than  s2  when  taken  to  be
65       unsigned characters.
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68       The  memcpy()  function  copies  n  bytes from memory area s2 to s1. It
69       returns s1. If copying takes place between objects  that  overlap,  the
70       behavior is undefined.
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73       The  memmove()  function  copies  n bytes from memory area s2 to memory
74       area s1. Copying between objects that  overlap  will  take  place  cor‐
75       rectly. It returns s1.
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78       The  memset()  function  sets the first n bytes in memory area s to the
79       value of c (converted to an unsigned char). It returns s.
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USAGE

82       Using memcpy() might be faster than using memmove() if the  application
83       knows that the objects being copied do not overlap.
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ATTRIBUTES

86       See attributes(5) for descriptions of the following attributes:
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91       ┌─────────────────────────────┬─────────────────────────────┐
92       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
93       ├─────────────────────────────┼─────────────────────────────┤
94       │Interface Stability          │Stable                       │
95       ├─────────────────────────────┼─────────────────────────────┤
96       │MT-Level                     │MT-Safe                      │
97       ├─────────────────────────────┼─────────────────────────────┤
98       │Standard                     │See standards(5).            │
99       └─────────────────────────────┴─────────────────────────────┘
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SEE ALSO

102       string(3C), attributes(5), standards(5)
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NOTES

105       Overlap  between  objects  being copied can arise even when their (vir‐
106       tual) address ranges appear to be disjoint; for example, as a result of
107       memory-mapping  overlapping portions of the same underlying file, or of
108       attaching the same shared memory segment more than once.
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112SunOS 5.11                        4 Feb 2009                        memory(3C)