Memcpy man

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str1 before memcpy Geeks str1 after memcpy Quiz. Notes: 1) memcpy() doesn’t check for overflow or \0 2) memcpy() leads to problems when source and destination addresses overlap. memmove() is another library function that handles overlapping well. Write your own memcpy() and memmove() Ok, so it's not too strict too say that the only valid use for a string after getting passed to strtok is as an argument to strcpy, memcpy, free, or as the lhs to an assignment? and that after one of those calls the string becomes valid again.

The memcpy() function conforms to ANSI X3.159-1989 (“ANSI C89”). HISTORY The memcpy () function first appeared in AT&T System V UNIX and was reimplemented for 4.3BSD-Tahoe . The memcpy_s(), memmove_s(), and memset_s() functions cannot be used safely in a multithreaded application due to the runtime constraint handler. For more information, see the runtime_constraint_handler(3C) man page. See Also

(POSIX and the C standards are explicit that employing memcpy() with overlapping areas produces undefined behavior.) Most notably, in glibc 2.13 a performance optimization of memcpy() on some platforms (including x86-64) included changing the order in which bytes were copied from src to dest. If the string length is known, then memcpy or memmove are more efficient than strcpy as they do not repeatedly check for the NUL terminator. They need a buffer length as a parameter, so they can't lead to buffer overflows in a manner similar to the aforementioned functions as long the supplied buffer length is right. The man page seems to imply that some implementations (though not musl) do suffer a performance hit when using memmove as opposed to memcpy. Moreover, appropriately using memmove and memcpy can communicate to code readers when data may or may not overlap. For these reasons, we default to memcpy, and use memmove only when necessary. About using memcpy on arrays: This is my first post, hope it complies with the standards. I'm working on locating the origin of the sound using libfreenect which is a library that enables communication between the Kinect and the computer.