Note that if the string is very small, performance will not be noticeable. memcpy () is used to copy a block of memory from a location to another. Copying structure in C with assignment instead of memcpy() C 库函数 - memcpy() C 标准库 - <string.h> 描述 C 库函数 void *memcpy(void *str1, const void *str2, size_t n) 从存储区 str2 复制 n 个字节到存储区 str1。 声明 下面是 memcpy() 函数的声明。 void *memcpy(void *str1, const void *str2, size_t n).. 菜鸟教程 -- 学的不仅是技术，更是梦想! In the age of Spectre only a memset_s with a memory barrier is secure, and currently all memset_s but my safeclib memset_s are insecure. How Struct Constructor Works in C++ - EDUCBA user November 30, -0001 at 12:00 am. The struct data type can contain other data types so is used for . Note that char arrays can't be assigned with string, so they need to be copied explicitly with additional functions like memcpy or memmove (see manual ). both GCC and clang emit a a series of movb instructions for copy_assignment, while emitting a single movl instruction for copy_memcpy. After thinking about it, assignment using memcpy () has a significant. Share answered Mar 21, 2011 at 16:53 Pointer variable D has been made to point to a new ListCell, as is shown in the diagram. Think of it this way: to memcpy() the struct is just a raw block of data. Note also that although in C memcpy and structure assignment are usually equivalent, in C++ memcpy and structure assignment are not equivalent. std::memmove - cppreference.com void *memcpy(void *dest, const void * src, size_t n) Parameters struct (C++) | Microsoft Docs Copying by straight assignment is probably best, since it's shorter, easier to read, and has a higher level of abstraction. Structure assignments have been supported since C90. Example #2. Typedef: C provides a capability that enables users to assign an alternate name to a data type. With respect to memmove() vs. memcpy() it is virtually guaranteed that memcpy will be faster than memmove. memcpy () is used to copy a block of memory from a location to another.