C / C ++ memcpy (a common function)

1. memcpy
   C library functions

void *memcpy(void *str1, const void *str2, size_t n)

Copies n characters to the store from the store str1 str2.
str1 - to the target array for storing copy content, type cast void * pointer.
str2 - point source data to be copied, cast type void * pointer.
n - the number of bytes to be copied.